英语词源字典 - 在线词源网站

lights (n.)[lights 词源字典]: "the lungs," c. 1200, literally "the light (in weight) organs," from light (adj.1); also see lung. Obsolete now except in phrases like to knock (someone's) lights out.[lights etymology, lights origin, 英语词源]
taps (n.): U.S. military signal for lights out in soldiers' quarters (played 15 minutes after tattoo), 1824, from tap (v.), on the notion of drum taps (it originally was played on a drum, later on a bugle). As a soldier's last farewell, played over his grave, it may date to the American Civil War. The tune was revised several times in mid-19c.