Regular and Irregular Verbs
Regular verbs are verbs which take a '-d' or '-ed' suffix in the past and past participle, as in
play, played, played and do not change in any other way. All other verbs are irregular.
Strong and Weak Verbs
Weak verbs are all verbs, including the regular verbs, which take a '-d' or '-ed' suffix in the past and past participle. Most weak verbs are regular. They are considered irregular when
a) the regular '-d / -ed' ending is contracted, as in
send, sent, sent (not 'sended') or
b) the vowel in the past and past participle is different from the vowel in the infinitive, as in
sell, sold, sold or
c) both of these changes occur, as in
bring, brought, brought.
Strong verbs do not take a '-d / -ed' suffix. Instead, the vowel in the past and past participle differs from the vowel in the infinitive, as in
take, took, taken. The past participle often ends in -n or -en. These verbs have mostly survived from conjugation systems which no longer exist. All strong verbs are irregular.
Classification of Irregular Verbs
Traditional classifications of irregular verbs tend to leave us each time with a mixed bag of morphologically heterogeneous verbs which, in some cases, have long since lost the features that justified their inclusion in a particular group. Any practical classification will therefore be based primarily on morphological considerations which are, however, still determined in a general way by grammar and / or etymology. Six basic groups (three mostly weak, three mostly strong) may be identified.
Weak Classes
1.1 Regular verbs like
cut, cut, cut, which keep the same form in infinitive, past and past participle (owing to contraction of the '-ed' ending).
1.2 Verbs like
sit, sat, sat, which keep the same form except that the (short) vowel in past and past participle differs from the (short) vowel in infinitive.
1.3 Verbs like
meet, met, met, which keep the same form except that the long vowel in infinitive is shortened in past and past participle.
1.4 Verbs like
lose, lost, lost, where the long vowel in infinitive is shortened in past and past participle, and which add a contracted regular ending ('-t').
1.5 Verbs like
send, sent, sent, which keep the same form except that the infinitive '-d' ending changes to '-t' in past and past participle.
1.6 Verbs like
make, made, made, where the infinitive ending changes to '-d' in past and past participle.
2.1 Verbs like
burn, burnt or burned, burnt or burned, which can add either irregular '-t' or regular '-ed' endings in past and participle but otherwise keep the same form.
2.2 Verbs like
pay, paid, paid, which are irregular only in spelling.
3.1 Verbs like
find, found, found which keep the same form except that the short vowel in infinitive is lengthened in past and past participle.
3.2 Mostly weak verbs like
think, thought, thought, where the short vowel in infinitive changes to ' -au' or ' -ou' and which take a ' -t' ending in past and past participle.
3.3 Verbs like
tell, told, told, which have vowel change and a regular '-d ending' in past and past participle.
Strong Classes
4.1 Verbs which follow the pattern of vowel modification seen in
sing, sang, sung.
4.2 Verbs which follow the pattern of vowel modification seen in
swing, swung, swung.
5.1 Verbs like
bite, bit, bitten, which have infinitive ending in '-t' or 'd' and participle in '-dden' or -'tten'.
5.2 Weak verbs like
melt, melted , melted or molten, which have an alternative irregular participle ending in '-en'.
5.3 Strong verbs like
give, gave , given which (mostly) show vowel change and participle in '-en'.
6.1 Verbs which follow the pattern of vowel modification of
blow, blew, blown in past and past participle.
6.2 Verbs like
sew, sewed, sewed or sewn, which have an alternative irregular participle ending in '-n'.
6.3 Verbs which follow the pattern of vowel modification of
wear, wore, worn.
6.4 Other verbs like
see, saw, seen with past participle ending in '-n'.