Some of the most common verbs in Latin (& English) are irregular, such sum, esse (am/is/was).

While regular verbs belong to specific conjugations and follow common rules when conjugated, IRREGULAR verbs follow their own unique set of rules when conjugated

Sum & Possum

Because SUM, ESSE is the most common irregular, an entire page has been dedicated to its forms.

Volo, Nolo, and Malo

The IMPERFECT and FUTURE tenses are formed relatively normally, using VOL- / NOL- / MAL- as stems and conjugating as a 3rd conjugation verb. There is no PASSIVE VOICE.

Present Subjunctive

Volo, Nolo, and Malo have irregular Present Subjunctive forms that need to be memorized, but they form their imperfect, perfect, and pluperfect subjunctives normally.

Perfect System

Volo, Nolo, and Malo form their PERFECT SYSTEM (perfect, pluperfect, future perfect tenses) normally--third principle part + endings--in both the indicative and subjunctive. There is no Perfect Passive System.

Participles & Infinitives & Imperatives

There are no participial forms of these verbs.

The infinitives form regularly, but only in the ACTIVE voice and there is no FUTURE tense.
Velle = to wish Voluisse = to have wished
Nolle = to not want Noluisse = to have not wished
Malle = to prefer Maluisse = to have preferred

There are no imperative forms for these verbs, but NOLO is used to form negative commands. For more on this, click here.

Eo, ire, ii, itum To Go

The verb eō, īre can be considered a semi-irregular verb as it borrows conjugation practices from both the 2nd conjugation and the 4th conjugation.

Its conjugations are very familiar, but perhaps strange in appearance given that its stem in both the present and perfect systems is simply “i”.

Additionally, there are no PASSIVE verb forms for eō, īre , except in the 3rd person singular, functioning as an impersonal verb (it is gone).

Present System (Present, Imperfect, Future)

Fero, ferre, tuli, latum to bear, carry

One of the most common Latin verbs (along with its numerous compounds) is fero, ferre (to bring, to carry).

This verb is irregular in two ways.

1. The stem changes dramatically from its 1st & 2nd principal parts to its 3rd pp and then again to its 4th pp.

This stem change is due to the fact that fero, ferre is defective and originally only had present system forms. And so, its 3rd & 4th principal parts are taken from another verb (tollo, tollere, sustuli, sublatum) in a process known as suppletion.

2. In the PRESENT TENSE & IMPERATIVE, there are irregular forms in which the “i” has been dropped through a process of syncopation.

Subjunctives