sleeper -
a spy or saboteur or terrorist planted in an enemy country who lives there as a law-abiding citizen until activated by a prearranged signal
undercover agent,
spy (military) a secret agent hired by a state to obtain information about its enemies or by a business to obtain industrial secrets from competitors
terrorist a radical who employs terror as a political weapon; usually organizes with other terrorists in small cells; often uses religion as a cover for terrorist activities
sleeper nest a nest of sleepers awaiting a prearranged signal; "sleeper nests of Islamic terrorists were capable of launching major attacks in Europe"
sleeper -
an unexpected hit; "that movie was the sleeper of the summer"
sleeper -
a piece of furniture that can be opened up into a bed
article of furniture,
furniture,
piece of furniture furnishings that make a room or other area ready for occupancy; "they had too much furniture for the small apartment"; "there was only one piece of furniture in the room"
sleeper -
pajamas with feet; worn by children
sleeper -
an unexpected achiever of success; "the winner was a true sleeper--no one expected him to get it"
sleeper -
a passenger car that has berths for sleeping
sleeper -
A type of pajama for a person, especially a child, that covers the whole body, including the feet.
sleeper -
An automobile which, not too quick out of the factory has been internally modified to excess, while retaining a mostly stock appearance in order to fool opponents in a drag race.