The Collaborative International Dictionary of English v.0.48:
slither \slith"er\ (sl[i^][th]"[~e]r), v. i. [Cf. G. schlittern, LG. schliddern. See slide.] To slide; to glide. [Prov. Eng.] [1913 Webster]WordNet (r) 3.0 (2006):
slither v 1: to pass or move unobtrusively or smoothly; "They slid through the wicket in the big gate" [syn: slither, slide]