acting or done surreptitiously, unofficially, or without warning:a sneak thief a sneak preview
1British (especially in children’s use) someone who informs an adult or person in authority of a companion’s misdeeds; a telltale: Ethel was the form sneak and goody-goody a furtive and contemptible person:he was branded a prying sneak for eavesdropping on intimate conversation
) North Americanshort for sneaker.
1 [no object, with adverbial of direction] move or go in a furtive or stealthy way:I sneaked out by the back exit [with object and adverbial of direction] convey (someone or something) in a furtive or stealthy way:someone sneaked a camera inside [with object] do or obtain (something) in a stealthy or furtive way:she sneaked a glance at her watch
(sneak up on
) creep up on (someone) without being detected:he sneaks up on us slyly
2 [no object] British informal (especially in children’s use) inform an adult or person in authority of a companion’s misdeeds; tell tales:she sneaked on us