Old English slæpere "one who sleeps, one who is inclined to sleep much," agent noun from sleep (v.). Meaning "strong horizontal beam" is from c. 1600. Meaning "dormant or inoperative thing" is from 1620s. Meaning "railroad sleeping car" is from 1875. Sense of "something whose importance proves to be greater than expected" first attested 1892, originally in American English sports jargon, probably from earlier (1856) gambling slang sense of "unexpected winning card." Meaning "spy, enemy agent, terrorist etc. who remains undercover for a long time before attempting his purpose" first attested 1955, originally in reference to communist agents in the West.
权威例句
1. She was usually a light sleeper.
她通常很容易惊醒。
2. I usually go up to London on the sleeper.
我一般都乘卧车去伦敦.
3. Please don't make any noise — my mother's a very light sleeper.
请安静——我母亲睡觉很轻.
4. The British call a railroad tie a sleeper.
英国人把“railroadtie” (铁路枕木)称为“sleeper”.
5. I crammed my bag full of swimsuits and T-shirts and caught the sleeper down to Beziers.