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Welcome to the Part-of-Speech Tags Tutorial! 

This site is composed to aid internet users involved in our research project to decide the correct Part-of-Speech (POS) tags for words. 

Our POS Tags are based on Penn Treebank. The definition of all POS tags are available on the main page (this page). 

Some of the binary classification rules (relationships and differences of two tags) are indexed in the side bar. The rules are sorted according to the tags (in ascending alphabet order). 

In each rule, the definitions of two tags are linked back to main page. Moreover, the relationships and differences are further interpreted if necessary.  

During the development of our project, the major observed ambiguities will also be reported. 


Most materials presented on this site are cited and compiled from internet resources. I will try to list all citations properly. The materials listed on this site are only for research project. None of the information is or will be used for any commercial purpose. If any listed material, in any form, violates the copyright law, please contact me immediately and I will remove the relevant content.  

Part-of-Speech Tags


Coordinating Conjunctions

Coordinating conjunctions connect words, phrases, and clauses. And, but, for, nor, or, so, and yet —these are the seven coordinating conjunctions. 



Cardinal Numbers

Unless used as list markers (LS), all cardinal numbers except for ONE are tagged CD, whether spelled out, in numeral form, or in some combination of the two.

Notice the difference between cardinal numbers with ordinal numbers, which are tagged as adjectives. 



A determiner is a noun-modifier that expresses the reference of a noun or noun phrase in the context, rather than attributes expressed by adjectives. This function is usually performed by articles, demonstratives, possessive determiners, or quantifiers.

In our POS tag set (Treebank set), articles and demonstratives are tagged as DT.  Possessive determiners are usually tagged as Possessive Pronouns (PRP). 


Existence There

See ref EX_RB


Foreign Words

The definitions of foreign words are vague systems from systems. In our project, if a potential foreign word has an entry in the OED(Oxford English Dictionary), it is not tagged as FW. 

Foreign names and certain common Latin liturgical texts are treated as proper nouns.

Foreign language titles are generally tagged FW. 

In foreign language sequences, everything (words, symbols, numbers, etc.) except punctuation is labelled FW.


Prepositions and Subordinating Conjunctions

A preposition links nouns, pronouns and phrases to other words in a sentence. The word or phrase that the preposition introduces is called the object of the preposition. A preposition usually indicates the temporal, spatial or logical relationship of its object to the rest of the sentence. Here is an incomplete list of prepositions:

Subordinating Conjunctions 

Some sentences are complex. Such sentences have two clauses, one main [or independent] and one subordinate [or dependent]. These are the patterns for a complex sentence:

The essential ingredient in a complex sentence is the subordinate conjunction:

after, once, until,  although,  provided that, when, as, rather than, whenever, because, since, where, before, so that, whereas, even if, than, wherever, even though, that, whether, if, though, while, in order that, unless, why

The subordinate conjunction has two jobs. 

  1. It provides a necessary transition between the two ideas in the sentence. This transition will indicate a time, place, or cause and effect relationship;
  2. To reduce the importance of one clause so that a reader understands which of the two ideas is more important. The more important idea belongs in the main clause, the less important in the clause introduced by a subordinate conjunction.



Adjectives describe nouns by answering one of these three questions: 
  • What kind is it? 
  • How many are there? 
  • Which one is it? 
An adjective can be a single word, a phrase, or a clause.


Comparative Adjectives

Form the comparative and superlative forms of a one-syllable adjective by adding –er for the comparative form and –est for the superlative.

One-Syllable Adjective Comparative Form  Superlative Form 
tall  taller  tallest 
old  older      oldest 
long  longer  longest 

If the one-syllable adjective ends with an e, just add –r for the comparative form and –st for the superlative form.

One-Syllable Adjective ending with final e Comparative Form  Superlative Form 
large larger  largest
wise wiser      wisest 

If the one-syllable adjective ends with a single consonant with a vowel before it, double the consonant and add –er for the comparative form; and double the consonant and add –est for the superlative form.

One-Syllable Adjective ending with a single consonant and a single vowel before it Comparative Form  Superlative Form 
big bigger  biggest
thin thinner      thinnest 
 fat  fatter fattest 

With most two-syllable adjectives, you form the comparative with more and the superlative with most.  Notice that  more and most themselves are still tagged as comparative / superlative adverbs, even they are combined with comparative / superlative adjectives.  
Two-Syllable Adjective Comparative Form  Superlative Form 
peaceful more peaceful  most peaceful
pleasant more pleasant      most pleasant
careful more careful  most careful 
thoughtful  more thoughtful  most thoughtful 

If the two-syllable adjectives ends with –y, change the y to i and add –er for the comparative form. For the superlative form change the y to i and add –est.

Two-Syllable Adjective ending with y Comparative Form  Superlative Form 
happy happier happiest
angry angrier      angriest
busy busier  busiest 

Two-syllable adjectives ending in –er, -le, or –ow take –er and –est to form the comparative and superlative forms.

Two-Syllable Adjective ending with -er -le -ow -er -est Comparative Form  Superlative Form 
narrow narrower narrowest
gentle gentler      gentlest

For adjectives with three syllables or more, you form the comparative with more and the superlative with most.  Notice that  more and most themselves are still tagged as comparative / superlative adverbs, even they are combined with comparative / superlative adjectives. 

Adjective with three or more Syllables Comparative Form  Superlative Form 
generous more generous most generous
important more important  most important
intelligent more intelligent most intelligent 


Exception 1:  Irregular adjectives

Irregular Adjective Comparative Form  Superlative Form 
good better best
bad worse     worst
far farther  farthest 
little less  least 
many more most 

Notice that more and most are tagged as comparative / superlative adjectives when they function as adjectives themselves (not modifying adjectives or adverbs).  

Exception 2: Two-syllable adjectives that follow two rules

Two-Syllable Adjective Comparative Form  Superlative Form 
clever cleverer cleverest
clever more clever most clever
gentle gentler  gentlest 
gentle more gentle  most gentle 
friendly friendlier friendliest 
friendly  more friendly  most friendly 
quiet  quieter  quietest 
quiet  more quiet  most quiet 
simple  simpler  simplest 
simple  more simple  most simple 


Superlative Adjectives



List Item Markers

Sometimes numbers and alphabets can also be list item markers, for example: 

1. ,   2.,  a, a., ....


Modal Verbs

The modal verbs in English are as follows, paired as present and preterite forms.

shall and should
will and would
may and might
can and could
mote (Archaic) and must


Common Nouns (Singular or Mass)


Common Nouns (Plural)

NNS is the tag of plural forms of common nouns. We can divide countable nouns into two large groups: regular and irregular.
Regular countable nouns make their plurals
  1. by adding -s or -es to the singular form;
  2. by changing final y to i and adding -es if the singular ends in a consonant + y. Note: Nouns ending in a vowel + y do not change y to i and then add -es.

Irregular countable nouns make their plurals in special ways:

  1. Some nouns ending in f change the f to v and then add -es.
  2. Some nouns have the same singular and plural forms.
  3. Some nouns use plural forms from other languages--not from English.



Proper Nouns (Singular)

Nouns name people, places, and things. Every noun can further be classified as common or proper. 

A proper noun has two distinctive features: 
  • it will name a specific [usually a one-of-a-kind] item, and
  • it will begin with a capital letter no matter where it occurs in a sentence.

Britney, Paris, Rover, Nike

Sometimes, proper nouns contain two or more important words.


Britney Spears, Central Park Zoo, Pacific Ocean

If this is the case, both important words are capitalized, and the whole thing is still considered to be one proper noun even though it's made up of more than one word.


Proper Nouns (Plural)

Names of Nations and Nationalities


the two Germans

Personal Names:


three Billys in the same classroom
Jones and Chavez  ==>  Joneses and Chavezes    (names ending in -es or -ez  get extra -es )

Italicized Names:

An italicized proper noun, like the title of a periodical, book, or movie, should have a nonitalicized s appended.


three consecutive Washington Posts
a stack of Catcher in the Ryes
all three Mission Impossibles



Determiners are divided into three main groups:
1. central determiners (the articles and other words such as “my,” “this,” and “some” that also function as pronouns);
2. predeterminers (for example “all,”“both,”“twice,”“such,”);
3. post determiners (for example “many,”“few,”“several”, the Numerals).

Predeterminers occur prior to other determiners (as you would probably guess from their name). This class of words includes multipliers (double, twice, four/five times . . . .); fractional expressions (one-third, three-quarters, etc.); the words both, half, and all; and intensifiers such asquite, rather, and such.

The multipliers precede plural count and mass nouns and occur with singular count nouns denoting number or amount:


My wife is making double my / twice my salary.

In fractional expressions, we have a similar construction, but here it can be replaced with "of" construction.


Charlie finished in one-fourth [of] the time his brother took.
Two-fifths of the respondents reported that half 
the medication was sufficient.

The intensifiers occur in this construction primarily in casual speech and writing and are more common in British English than they are in American English. 

This room is rather a mess, isn't it?
The ticket-holders made quite a fuss when they couldn't get in.
Our vacation was such 
a grand experience.

Half, both, and all can occur with singular and plural count nouns; half and all can occur with mass nouns. There are also "of constructions" with these words ("all [of] the grain," "half [of] his salary"); the "of construction" is required with personal pronouns ("both of them," "all of it"). The following chart (from Quirk and Greenbaum) nicely describes the uses of these three predeterminers:


Possessive Endings  's

Notice the difference with the abbreviations of be, such as       he is = he's,  it is = it's.

When we want to show that something belongs to somebody or something, we usually add 's to a singular noun and an apostrophe ' to a plural noun.


the boy's ball
the boys' ball

With Proper Nouns

We very often use possessive 's with names:


This is Mary's car.
Where is Ram's telephone?
Who took Anthony's pen?
I like Tara's hair.

When a name ends in s, we usually treat it like any other singular noun, and add 's:

This is Charles's chair.

But it is possible (especially with older, classical names) to just add the apostrophe '.

Who was Jesus' father?

With Irregular Plurals 

Some nouns have irregular plural forms without s (man > men). To show possession, we usually add 'sto the plural form of these nouns:

 singular noun plural noun
 my child's dog my children's dog
 the man's work the men's work
 the mouse's cage the mice's cage
 a person's clothes people's clothes


Possessive Pronouns




Adverbs are words that modify a verb (answer question how), an adjective (answer question how), another adverb (answer question how)

Kind of adverbs
  • Adverbs of Manner        For example, slowly, quietly
  • Adverbs of Place        For example, there, far
  • Adverbs of Frequency     For example, everyday, often 
  • Adverbs of Time         For example, now, first, early
Positions of adverbs

One of the hallmarks of adverbs is their ability to move around in a sentence. Adverbs of manner are particularly flexible in this regard.

Solemnly the minister addressed her congregation.
The minister solemnly addressed her congregation.
The minister addressed her congregation solemnly

The following adverbs of frequency appear in various points in these sentences:


Before the main verb:   I never get up before nine o'clock.
Between the auxiliary verb and the main verb:  I have rarely written to my brother without a good reason.
Before the verb used to:   I always used to see him at his summer home.

Indefinite adverbs of time can appear either before the verb or between the auxiliary and the main verb:

He finally showed up for batting practice
She has recently retired


Comparative Adverbs

LY Adverbs

With LY adverbs (adverbs formed from adjectives by adding -ly to the end) we form the comparative and superlative forms with more and most.

Adjective Adverb  Comparative Form  Superlative Form 
quiet quietly more quietly most quietly 
careful carefully     more carefully most carefully 
happy happily  more happily  most happily 

Notice: In comparative / superlative adverbs, more and most are also tagged as RBR/RBS .  

Other Adverbs

For adverbs which retain the same form as the adjective form, we add -er to form the comparative and -est to form the superlative.

Adjective Adverb  Comparative Form  Superlative Form 
hard hard harder hardest
fast fast     faster fastest 
early early  earlier earliest

Irregular Adverbs

Adjective Adverb  Comparative Form  Superlative Form 
good well better best
bad badly     worse worst 
far far  farther/further farthest/furthest


Superlative Adverbs




Particles are short words that with just one or two exceptions are all prepositions unaccompanied by any complement of their own. Some of the most common prepositions belonging to the particle category:

along, away, back, by, down, forward, in, off, on, out, over, round, under, up







An interjection is a word added to a sentence to convey emotion. It is not grammatically related to any other part of the sentence.

A: aha, ahem, ahh, ahoy, alas, arg, aw

B: bam, bingo, blah, boo, bravo, brrr

C: cheers, congratulations

D: dang, drat, darn, duh

E: eek, eh, encore, eureka

F: fiddlesticks

G: gadzooks, gee, gee whiz, golly, goodbye, goodness, good grief, gosh

H: ha-ha, hallelujah, hello, hey, hmm, holy buckets, holy cow, holy smokes, hot dog, huh?, humph, hurray

O: oh, oh dear, oh my, oh well, ooops, ouch, ow

P: phew, phooey, pooh, pow

R: rats

S: shh, shoo

T: thanks, there, tut-tut

U: uh-huh, uh-oh, ugh

W: wahoo, well, whoa, whoops, wow

Y: yeah, yes, yikes, yippee, yo, yuck


Verbs (base form)

English verbs have five basic forms: the base (VB and VBP), -S (VBZ), -ing (VBG), past (VBD), and past participle forms (VBN). 

Most verbs have identical base forms (VB) and non-3rd personal singular present form (VBP). The difference is maninly dependent on their roles in sentences. 

When verbs appear in their base forms, the usages can be categorized as follows:

  1. Infinitive (usually after to, or, after a model verb)

          It's always easier to learn something than to use what you've learned.

          He can't study at home. 

      2.  Imperative mood with commanding and demanding


          Go to the edge of the cliff and jump off. Build your own wings on the way down.

      3.  Subjunctive verb    (Source:

           The subjunctive is a special, relatively rare verb form in English. The structure of the subjunctive is extremely simple. For all verbs except the past tense of be, the subjunctive is the same as the bare infinitive (infinitive without "to").

           The subjunctive does not change according to person (I, you, he etc). So subjunctive usage of verbs are tagged as base form verbs (VB).

           For example, we use the subjunctive when talking about events that somebody:

    • wants to happen
    • hopes will happen
    • imagines happening

            Examples (be):

            The President requests that you be present at the meeting.

            It is vital that you be present at the meeting.

            If you were at the meeting, the President would be happy.

            The subjunctive is typically used after two structures:

    • the verbs: ask, command, demand, insist, propose, recommend, request, suggest + that
    • the expressions: it is desirable, essential, important, necessary, vital + that


            The manager insists that the car park be locked at night.

            The board of directors recommended that he join the company.

            It is essential that we vote as soon as possible.

            It was necessary that every student submit his essay by the weekend.

          Some fixed expressions use the subjunctive. Here are some examples:            


             Long live the King!

             God bless America!

             Heaven forbid!

             Come what may, I will never forget you.

            Notice that in these structures the subjunctive is always the same. It does not matter whether the sentence is past or present. Look at these examples:


            Present: The President requests that they stop the occupation.

            Past: The President requested that they stop the occupation.

            Present: It is essential that she be present.

            Past: It was essential that she be present.


Verbs (past tense)

The purpose of past tense verbs within the English language is to express activity, action, state, or being in the past. A simple past tense verb always has just one part. You need no auxiliary verb to form this tense.


We visited the grocery store yesterday.    Visited is a simple past tense verb that is used to describe a completed action.
Emily said that she went to the mall.  Said is a past perfect tense verb that describes reported speech.



Verbs (gerund or present participle)

  • Usually add -ing
  • When the verb ends in an e, we drop the e and add ing
  • If a one syllable (with only one vowel sound) verb ends in one consonant (for example p, t, r) that follows one vowel (for example a, o, e), we double the consonant
  • Some verbs have irregular -ing form:
  • lie      lying                           die             dying                          travel         Br. travelling      Am. traveling


Verbs (past participle)

The past participles for regular verbs are the same as their past forms (look-looked-looked and study-studied-studied), for example. For irregular verbs, the past and past participle forms are different (for example, be- was/were-been and go-went-gone).

The past participle is commonly used in several situations:

  • Past participles are used as part of the present and past perfect tenses (both "regular" and continuous). 
          The non-continuous present perfect tense uses has or have + the past participle; the present perfect continuous tense uses has or have + been (the past participle of BE) + the - ing form of the main verb.


         He has (He's) taken a vacation. / He has (He's) been taking a vacation.

            I have (I've) taken my medicine. / I have (I've) been taking that medicine for three days.

             The non-continuous past perfect tense uses had + the past participle; the past perfect continuous tense uses had + been + the - ing form of the main verb.


            She had (She'd) lived here for 10 years when I met her. /   She had (She'd) been living here for 10 years when I met her.
            He had (He'd) waited a long time before he left. /    He had (He'd) been waiting a long time before he left.

  • Past participles are also used to make one of the past forms for the modal verbs (modal auxiliaries). These forms use a modal + have + the past participle.

            could have gone             may have been             should have known             might have seen             would have written             must have forgotten

  • Another use for past participles is as participial adjectives (verb forms used as adjectives). Participial adjectives may be used both in single and in phrases.

             We were bored / excited / interested.              We were bored with / excited about / interested in the movie.              It's broken / gone / done.              It's broken into two pieces / gone from where I usually put it / done by machine, not by hand.              Abandoned, he didn't know what to do.              Abandoned by everyone he had considered to be his friends, he didn't know what to do.



Verbs (non 3rd person singular present)

The singular present tense in English expresses habits and routines, general facts and truths, and thoughts and feelings. 
The non 3rd person singular present form is identical to the base form of the verb, which is defined as the infinitive without the preposition to. 


Verbs (3rd person singular present)

Forming Regular Third Person Singular Present Tense Verbs

To form the third person singular present tense form of most regular English verbs, simply affix the suffix -s to the end of the verb. For example, the following list includes the infinitive, base form, and third person singular present tense form some common English verbs:

  • to argue – argue – argues
  • to clean – clean – cleans
  • to fight – fight – fights
  • to pickle – pickle – pickles
  • to wonder – wonder – wonders

For verbs that end in an -s-z-x-ch, or -sh, affix the suffix -es to the end of the verb. For example:

  • to box – box – boxes
  • to catch – catch – catches
  • to kiss – kiss – kisses
  • to watch – watch – watches
  • to wish – wish – wishes

For verbs spelled with a final y preceded by a consonant, change the y to an i and then affix the ­-es suffix. For example:

  • to apply – apply – applies
  • to copy – copy – copies
  • to identify – identify – identifies
  • to reply – reply – replies
  • to try – try – tries



what (whatever) and which, when they occur NOT at the beginning of a sentence.   At the beginning of a sentence, they have tags WP.  

Exception: if what is followed by an article, no matter which position it is, it is tagged as WDT. 



A pronoun which is spelt with an initial wh. (How is also included, though the h and w are in an unusual order!):

What, Which, who, whoever 

Notice the exceptions that what and which are tagged as Wh-determiners.


Possessive wh-pronoun

whom, whose



A special subclass of adverbs includes a set of words beginning with wh-.

The most common are 

when, where, why, how, whence, whereby, wherein, whereupon, and how

There are some additional POS tags for punctuation marks. There labels are mostly fixed by the tokens (closed form tags). 


Pound sign


Dollar mark


Right hand side double or single quotations

' '

Right hand side double or single  quotations


Non-full stop break punctuation marks for the sentence

(  or  LRB

Left hand side brackets

) or RRB

Right hand side brackets


Full stop marks of sentences,  including    . (full stop),    ? (question mark),    ! (exclamation point).


Colon :  and semi-colon ;

Classification Rules of Tags

Please see the side bar links.

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