Sleeper word meaning and definition

[noun] an unexpected hit; "that movie was the sleeper of the summer"
[noun] tropical fish that resembles a goby and rests quietly on the bottom in shallow water
[noun] a piece of furniture that can be opened up into a bed
[noun] a passenger car that has berths for sleeping
[noun] one of the cross braces that support the rails on a railway track; "the British call a railroad tie a sleeper"
[noun] a rester who is sleeping
[noun] an unexpected achiever of success; "the winner was a true sleeper--no one expected him to get it"
[noun] a spy or saboteur planted in an enemy country who lives there as a law-abiding citizen until activated by a prearranged signal

\Sleep"er\, n. 1. One who sleeps; a slumberer; hence, a drone, or lazy person. 2. That which lies dormant, as a law. [Obs.] --Bacon. 3. A sleeping car. [Colloq. U.S.] 4. (Zo["o]l.) An animal that hibernates, as the bear. 5. (Zo["o]l.)
(a) A large fresh-water gobioid fish ({Eleotris dormatrix}).
(b) A nurse shark. See under {Nurse}.
\Sleep"er\, n. [Cf. Norw. sleip a sleeper (a timber), as adj., slippery, smooth. See {Slape}.] Something lying in a reclining posture or position. Specifically:
(a) One of the pieces of timber, stone, or iron, on or near the level of the ground, for the support of some superstructure, to steady framework, to keep in place the rails of a railway, etc.; a stringpiece.
(b) One of the joists, or roughly shaped timbers, laid directly upon the ground, to receive the flooring of the ground story. [U.S.]
(c) (Naut.) One of the knees which connect the transoms to the after timbers on the ship's quarter.
(d) (Naut.) The lowest, or bottom, tier of casks.

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