Proto-Indo-European Verbs - Conjugations

Conjugations

PIE, like many languages, had a set of conjugational classes for verbs, called "conjugations". In many modern languages, and to a fair extent in Latin, each verb lexeme belongs to a particular conjugation which determines all verb forms. In PIE, however, a verb lexeme would belong to one conjugation for each of the three aspects (imperfective, perfective, stative), with no clear relations among them. This leads to the system of describing a verb by its principal parts, one for each of the conjugational classes that a verb belongs to. (Latin has four principal parts, Ancient Greek six, and Sanskrit at least ten.)

For example, in Sanskrit, there are at least ten present conjugations, seven aorist conjugations, and five perfect conjugations, and in general, knowing the present conjugation of a verb does not help in identifying the aorist or perfect conjugation, and vice-versa. Furthermore, especially in Greek and Sanskrit, many verbs are missing some principal parts, and some verbs can be conjugated in some aspects according to multiple conjugations, sometimes with different meanings (see the above example with the Greek verb peithō).

This can also be seen in the third conjugation of Latin, which includes most verbs directly inherited from PIE. In the Latin third conjugation, verbs in the present tense can be either normal or i-stem, while verbs in the perfect can be formed in any of six or so different ways, and there is no general relation between the two.