Thus far, we have been using the terms "weak verb" and "strong verb". This has proved sufficient for using present tense and future tense. But it is only half of the story.
Thamil verbs have been divided up into 7 verb classes. What is remarkable about Thamil is that all verbs belong to 1 of the 7 verb classes. The verbs of any particular class all follow the same pattern when it comes to making the past, present, and future tenses. Only relatively few words are irregular. (We have already come across 2 -- வா and போ.) Some exceptions exist to the general patterns of these verb classes, but such exceptions are minimal.
What we thought of as weak verbs is a generalization of Classes 1-4. Strong verbs are from Classes 6 and 7. Class 5 contains irregulars. It will not be discussed properly within the main lessons, but it can be found at Appendix A. Since most of the verbs that belong to a class have common characteristics, it will be helpful to memorize one verb from each class as a reference for other verbs in that class.
|1||1-syllable, short vowel, ends in -ய், -ள், -ல்||(see below)|
|1a||ends in -ய்||செய்|
|1b||ends in -ள்||ஆள்|
|1c||ends in ல்||செல்|
|2||2 syllables, ends in -ய், -ர், -ழ், -இ, -ஐ||வளர்|
|3||ends in -உ (exception -டு, -று -- see below)||பேசு|
|4||ends in -டு, -று||போடு|
|6||combination of Class 2 and Class 4 patterns||கொடு|
|7||ends in -அ||நட|
The ultimate determiner to which class a verb belongs is not the verb root, but the way it forms past and present/future tenses. (It will become clearer after the next lesson on the Past Tense.) This explains why அழு is a Class 1a verb and சேர் is a Class 2 verb.
Note that there are probably no more than 10 or so verbs in Class 5. However, (even fewer) irregular verbs may appear in other classes. In particular, remember that வான் and போ are irregular verbs. However, வா is a Class 2 verb, but போ fits into Class 3. Also, இரு is a Class 7 verb.