Synonyms for Day Lily (same or very similar meaning)
WordNet sense 1 (any of numerous perennials having mounds of sumptuous broad ribbed leaves and clusters of white, blue, or lilac flowers; used as ground cover):
plantain lilyWordNet sense 2 (any of numerous perennials having tuberous roots and long narrow bladelike leaves and usually yellow lilylike flowers that bloom for only a day):
daylilyFrom the ODE community, based on WordNetadd/edit