language: humans languages collectively, tools for communication. There are three common humans languages: speaking, writing, and sign language.
letter: a symbol distinguishing words.
word: a unit representing meaning in a sentence.
phrase: several words together to represent a meaning.
sentence: a unit expressing a complete thought that begins with a capital letter and ends with a full stop (period), a question mark, or an exclamation mark.
morpheme: parts of a word that still represent a meaning.
syllable: a group of phonetic alphabets having one vowel, with or without surrounding consonants.
phoneme: what an international phonetic alphabet represent.
arbitrariness: In linguistics, arbitrariness is the absence of any natural or necessary connection between a meaning and its linguistic form.
the principle of least effort: The principle of least effort is to do less and to accomplish a task.