[n] a covering that serves to conceal or shelter something; "they crouched behind the screen"; "under cover of darkness"
[n] a flock of coots
[adj] secret or hidden; not openly practiced or engaged in or shown or avowed; "covert actions by the CIA"; "covert funding for the rebels"
[adj] (law) of a wife; under the protection of her husband
backstair, backstairs, black, clandestine, cloak-and-dagger, cloaked, closet(a), collusive, concealment, conniving, cover, disguised, furtive, hole-and-corner(a), hugger-mugger, hush-hush, masked, on the quiet(p), protected, screen, secret, secure, sub-ro