Definitions

1. 1.The infinitive suffix for many verbs. Usually indicates an imperfective verb.
2. 2.Used in place of -я́ть (-játʹ) after the hushing sibilants ш щ ч ж and after жд, when used to derive imperfective verbs from (normally but not always prefixed) perfective class 4 verbs (in -ить (-itʹ)) following one of т д с з ш ж ч щ. Always stressed. Triggers iotation of the final stem consonant, but it is unpredictable whether the iotation of т results in ч or щ and whether the iotation of д results in ж or жд. Very occasionally found with class 5 verbs in -еть (-etʹ).
3. 3.Used to derive imperfective verbs from certain classes of prefixed perfective verbs, where the stem ends in a non-palatal consonant, e.g. class 3 (-нуть (-nutʹ)), class 6 (some -ать (-atʹ), particularly where the present tense does not end in -аю (-aju)), class 7 (-ть (-tʹ) after a consonant and -ти (-ti)), class 8 (-чь (-čʹ)). Always stressed (which may be the only difference between the perfective and imperfective forms, esp. for class 6 perfectives). It is added to the underlying stem, minus the infinitive suffix. In some cases, the underlying stem is not apparent in the infinitive. In such a case, the stem may appear in the present tense (in class 7 verbs such as напа́сть (napástʹ), underlying stem напа́д- visible in present 1st singular нападу́ (napadú), or in class 8 verbs such as отсе́чь (otséčʹ), underlying stem отсе́к- visible in present 1st singular отсеку́ (otsekú)) or may not (in class 3 verbs in -нуть, e.g. поки́нуть (pokínutʹ), underlying stem поки́д-).
4. 4.Occasionally, irregularly used to derive imperfective verbs from (normally but not always prefixed) perfective class 4 (-ить (-itʹ)) and class 5 (some -еть (-etʹ)) verbs where the stem ends in a paired palatal consonant. Always stressed. Does not trigger iotation.

Forms