From WordNet (r) 3.0 (2006) [wn]:
snack
n 1: a light informal meal [syn: bite, collation, snack]
v 1: eat a snack; eat lightly; "She never loses weight because
she snacks between meals" [syn: nosh, snack]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Snack \Snack\, n. [See Snatch, v. t.]
1. A share; a part or portion; -- obsolete, except in the
colloquial phrase, to go snacks, i. e., to share.
[1913 Webster]
At last he whispers, "Do, and we go snacks." --Pope.
[1913 Webster]
2. A slight, hasty repast. [Colloq.]
[1913 Webster]