Old English snaca, from Proto-Germanic *snakon (cf. Old Norse snakr "snake," Swedish snok, German Schnake "ring snake"), from PIE root *snag-, *sneg- "to crawl, creeping thing" (cf. Old Irish snaighim "to creep," Lithuanian snake "snail," Old High German snahhan "to creep"). In Modern English, gradually replacing serpent in popular use. Meaning "treacherous person" first recorded 1590 (cf. Old Church Slavonic gadu "reptile," gadinu "foul, hateful").
Snake eyes in crap-shooting sense is from 1929. Snake oil is from 1927. Snake-bitten "unlucky" is sports slang from 1957. The game of Snakes and Ladders is attested from 1907. Snake pit is from 1883, as a supposed primitive test of truth or courage; figurative sense is from 1941. Phrase snake in the grass is from Virgil's Latet anguis in herba [Ecl. III:93] Another Old English word for "snake" was næddre (see adder).
1650s, "to twist or wind (something) into the form of a snake," from snake (n.). The intransitive sense of "to move like a snake" is attested from 1848; that of "to wind or twist like a snake" (of roads, etc.) is from 1875. Related: Snaked; snaking.