listless (adj.)youdaoicibaDictYouDict[listless 词源字典]
mid-15c., from Middle English liste "pleasure, joy, delight" (see list (v.4)) + -less. Related: Listlessly; listlessness.[listless etymology, listless origin, 英语词源]
moon (v.)youdaoicibaDictYouDict
c. 1600, "to expose to moonlight;" later "idle about" (1836), "move listlessly" (1848), probably on notion of being moonstruck. The meaning "to flash the buttocks" is first recorded 1968, U.S. student slang, from moon (n.) "buttocks" (1756), "probably from the idea of pale circularity" [Ayto]. See moon (n.). Related: Mooned; mooning.