Irregular verb

The English verb normally has a maximum of five forms in present-day English. For two additional inflections current in Shakespeare's time, go to Verb-endings in older English.) The five different forms you will meet currently are:

• the base form - the simplest, used for the bare infinitive and most of the persons in the present tense;
• the 3rd person singular in the present tense, normally the base form + '-s' or '-ies';
• the past tense, normally formed with the suffix '-ed';
• the '-ed', or 'past', or 'passive' participle
  • in the regular verb, this too is normally formed with the suffix '-ed': the commonest irregularity in irregular verbs is variation between the past tense and the past participle (AWE uses the phrase past forms as a convenient label where a verb has identical writing of the past tense and the past participle);
• the '-ing', or 'present', or 'active' participle, normally formed with the suffix '-ing'.

Verbs that have four different forms which conform to the above, with the third and fourth inflections (the past tense and participle) identically formed with '-ed', are known as regular verbs to English grammar. Those that do not conform to the pattern, or have the past tense and past participle different, are irregular verbs. See the category:irregular verbs for a list of many of them. Quirk (1985) groups them into seven classes, with various sub-classes: each of these has its own sub-category in AWE.

For the only verb in English with more than five forms, ask yourself "Which is the only verb in English with more than five forms?" - and click this link for the answer.