Frightened rhymes with:
brightened, brightened, enlightened, heightened, lightened, tightened, unenlightened, brightened, buttoned, cottoned, disheartened, enlightened, fattened, flattened, heartened, heightened, heistand, hestand, hiestand, lightened, montand, predestined, shortened, smartened, straightened, sweetened, threatened, tightened, unbuttoned, unenlightened