Old Irish class B V verbs (Strachan's A2; McCone's S3 with i vocalism) are derived from Proto-Celtic verbs ending in *-nuti, from Proto-Indo-European athematic verbs with a nasal infix before w (singular *-né-w-ti, plural *-n-w-énti). They correspond to Ancient Greek verbs ending in -νυμι(-numi) and to Sanskrit class 5 verbs (e.g. शृणोति(śṛṇoti, “to hear”), which corresponds to Old Irish ro·cluinethar(“to hear”)). The stem-final n is always non-palatalized, and exists only in the present stem; there is no n in the future, subjunctive, or preterite stems of these verbs.
The inflection is almost identical to that of class B IV; the difference is that the root vowel in most cases is i, showing that the vowel after the n must have been u in Proto-Celtic.
A sample verb of this subclass is ·gnin (found in ad·gnin/as·gnin/in·gnin(“to know”)). The endings are as follows (note that several of the endings are delenited after the root-final n):