прилагательное секретный, тайный Например: undercover agent — тайный агент to work undercover, to go undercover — действовать в тайне от кого-либо Синоним(ы): secret, covert
I. adjective acting or executed in secret; specifically employed or engaged in spying or secret investigation Example: an undercover agent • undercover adverb II. noun a person engaged in undercover activity; spy