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