SLEEPER

n. 1 a person or animal that sleeps. 2 Brit. a wooden or concrete beam laid horizontally as a support, esp. for railway track. 3 a a sleeping-car. b a berth in this. 4 Brit. a ring worn in a pierced ear to keep the hole from closing. 5 a thing that is suddenly successful after being undistinguished. 6 a sleeping-suit. 7 a spy or saboteur etc. who remains inactive while establishing a secure position.