Origin and history of trove

mid-12c., tresor, tresour, "money or jewels in store, wealth accumulated, spoils hoarded," from Old French tresor "treasury, hoard, treasure" (11c., Modern French trésor), from Gallo-Roman *tresaurus, alteration of Latin thesaurus "treasury, treasure" (source also of Spanish tesoro, Italian tesoro), from Greek thēsauros "store, treasure, treasure house." This is related to tithenai "to put, to place," said to be from a reduplicated form of the PIE root *dhe- "to set, put," hence "lay down, make, create, etc."

Old English poets used goldhord, maðm for this idea. In Middle English the word sometimes became thresur, etc., in awkward imitation of the classical forms, as also in Old French; the modern spelling in English was established from 16c. 

The figurative sense of "anything valued" is by c. 1200, originally in spiritual senses; by c. 1300 as "person held dear." The children's treasure hunt is attested by 1913 (treasure-hunter for one who seeks hidden gold is by 1858). For treasure trove, see trove.