Definition of "sleeper" []

• One that sleeps: a heavy sleeper who was not wakened by the burglar. (noun)
• A sleeping car. (noun)
• Children's pajamas, usually with legs that cover the feet. Often used in the plural. (noun)
• One that achieves unexpected recognition or success, as a racehorse or movie. (noun)
• A spy or saboteur who is planted in an enemy country and who lives unobtrusively as a citizen of that country until activated into clandestine operations by a prearranged signal. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The term sleeper has simply taken on a new meaning and sleepers themselves are a bit harder to find."
• "Four years after that FBI report was written, the word sleeper moved from spookspeak jargon into the general language."
• "I've been looking and looking and all I can find for the Caledonia sleeper is the listing sandwiches, snacks, and a full British menu."