Meaning

verb to go stealthily or furtively

noun a person who is regarded as underhanded and furtive and contemptible

adjective marked by quiet and caution and secrecy; taking pains to avoid being observed

originPossibly from Middle English sniken (“to creep, crawl”), from Old English snīcan (“to creep, crawl”), from Proto-West Germanic *snīkan, from Proto-Germanic *snīkaną (“to creep, crawl”), which is related to the root of snake. Compare Danish snige (“to sneak”), Swedish snika (“to sneak, hanker after”), Icelandic sníkja (“to sneak, hanker after”). Possibly related to snitch.

Etymology from Wiktionary, CC BY-SA 3.0