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