1550s (implied in sneakish), "creep or steal about privately; move or go in a stealthy, slinking way" (intransitive); perhaps from some dialectal survival of Middle English sniken "to creep, crawl" (c. 1200), which is from Old English snican "to sneak along, creep, crawl," from Proto-Germanic *sneikanan, which is related to the root of snail and snake (n.).
The transitive sense of "insert stealthily" is by 1640s. That of "partake of or get surreptitiously" is from 1883. Related: Sneaking. To sneak up on someone or something is by 1869.
As an adjective, in reference to feelings, suspicions, etc., "not openly vowed, undemonstrative," from 1748. Sneak-thief, one who enters through unsecured doors and windows to steal, is recorded by 1859; the movies sneak-preview of a film before official release is from 1938.
"a sneaking person; person of selfish and cowardly temper and conduct," 1640s, from sneak (v.). By 1700 as "act or practice of sneaking."
updated on February 03, 2023