2.臥車；臥舖[C]I booked a first-class sleeper. 我訂了頭等臥舖車票。
3.臥底；潛伏者They activated their sleepers over there to plan on a terrorist attack on Paris. 他們啟動了埋伏的恐怖分子，準備對巴黎進行恐怖恐擊。
4.【主英】（鐵路）枕木[C]
5.【建】（地板的）稜木[C]
6.【美】出乎意料地獲得成功的人（或事物），爆冷門的人（或事物）[C]The football game was won by a sleeper, an unknown new player. 足球比賽爆冷門，有一匹黑馬贏球了，是一個名不見經傳的新球員。That movie was the sleeper of the year: suddenly everyone had to see it. 那部電影爆出冷門，成了今年的最佳影片。突然間，每一個人都不得不一睹為快。
