The Collaborative International Dictionary of English v.0.48:

Sneak \Sneak\ (sn[=e]k), v. i. [imp. & p. p. Sneaked
   (sn[=e]kt); p. pr. & vb. n. Sneaking.] [OE. sniken, AS.
   sn[imac]can to creep; akin to Dan. snige sig; cf. Icel.
   sn[imac]kja to hanker after.]
   1. To creep or steal (away or about) privately; to come or go
      meanly, as a person afraid or ashamed to be seen; as, to
      sneak away from company.
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            You skulked behind the fence, and sneaked away.
                                                  --Dryden.
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   2. To act in a stealthy and cowardly manner; to behave with
      meanness and servility; to crouch.
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