Sleeper

"Sleeper" has a number of different meanings, usually connected to sleep in varying degrees of literalness:

• Sleeper is a Woody Allen movie.
• In espionage, a sleeper is an agent left long inactive.
• In railroads, a synonym for sleeping car, or timbers supporting the rails (called ties in North America).
• In biology, fish of the family Eleotridae.
• In business, synonym for sleeping partner.
• Synonym for sleeping suit.
• In construction and shipbuilding, a strong internal beam.
• A sleeper is an automobile that has any manner of modified engine, drivetrain, suspension, brakes or other parts, with the goal of improving its original performance, while still maintaining the outward appearance of a stock, factory equipped vehicle.
• A sleeper is a type of couch.