/on"set', awn"-/ , n.
1. a beginning or start: the onset of winter.
2. an assault or attack: an onset of the enemy.
3. Phonet. the segment of a syllable preceding the nucleus, as the gr in great. Cf. coda (def. 5), core (def. 14).
[ 1525-35; ON + SET, after the v. phrase set on ]