Irregular verbs are verbs that do not add -d or -ed to the infinitive (or base form) to create the past, the past participle, or both forms.
Verbs are included that have both regular and irregular forms. For example, “learn” and “show” have both regular (learn - learned - learned) and irregular (learn - learnt - learnt) past and past participle forms.
The “infinitive” can be used with “to” (the full infinitive or to-infinitive) or without “to." These are called the the full infinitive or to-infinitive (e.g., to do, to dance, to put) and the bare infinitive or the base form of the verb (e.g., do, dance, put).
The infinitive is also used to create the gerund and the present participle verb forms by adding the -ing suffix to the base form (doing, dancing, putting).
In the gerund and present participle forms of the verb, spelling changes may occur. For example, depending on word, the final -e may be dropped (e.g., choose > choosing, make > making, shake > shaking) or the final single consonant preceded by a single vowel is doubled (e.g., cut > cutting, forbid > forbidding, get > getting). On this list, only the gerunds undergoing spelling changes are listed.
The past infinitive is created by using the auxiliary “have” and the past participle form of the verb (e.g., to have done, to have danced, to have put).