derby hat(n = noun.artifact) bowler, bowler hat, derby, plug hat - a felt hat that is round and hard with a narrow brim;
is a kind of chapeau, hat, lid

bad hat, billycock hat, bishop's hat, bowler hat, brass hat, campaign hat, cavalier hat, church hat, cocked hat, cowboy hat, derby, dress hat, felt hat, fur hat, gainsborough hat, hard hat, hat, hat shop, hat trick, high hat, iron hat, kentucky derby, mexican hat, old hat, opera hat, panama hat, picture hat, pith hat, plug hat, porkpie hat, safety hat, service hat, shovel hat, silk hat, slouch hat, straw hat, sun hat, ten-gallon hat, tin hat, top hat, woman's hat