truffle (n.)
type of edible underground fungus, 1590s, from Middle French trufle (14c.), probably from Old Provençal trufa, metathesized from Late Latin tufera (plural), cognate of Latin tuber "edible root." Another theory notes Italian tartuffo (Milanese tartuffel) "potato," supposedly from terræ tuber. Extended 1926 to powdered, round chocolates that look like truffles.