verb-intransitive. To go or move in a quiet, stealthy way.verb-intransitive. To behave in a cowardly or servile manner.v. To move, give, take, or put in a quiet, stealthy manner: sneak candy into one's mouth; sneaked a look at the grade sheet. n. A person regarded as stealthy, cowardly, or underhanded.n. An instance of sneaking; a quiet, stealthy movement.n. Informal A sneaker.adj. Carried out in a clandestine manner: sneak preparations for war. adj. Perpetrated without warning: a sneak attack.