treasure: [12] Treasure comes ultimately from Greek thēsaurós ‘treasure’, a word of unknown origin. This was borrowed into Latin as thēsaurus (acquired directly by English as thesaurus [19] with the metaphorical sense ‘treasury of knowledge, words, etc’), and it made its way into English via Vulgar Latin *tresaurus and Old French tresor. => thesaurus[treasure etymology, treasure origin, 英语词源]