9 letters · 12 points in Scrabble
noun a book containing a classified list of synonyms
origin16th century, borrowed from Latin thēsaurus, from Ancient Greek θησαυρός (thēsaurós, “storehouse, treasure”); its current English usage/meaning was established soon after the publication of Peter Roget's Thesaurus of English Words and Phrases in 1852. Doublet of treasure.
Etymology from Wiktionary, CC BY-SA 3.0