1. Any of several perennial Eurasian herbs of the genus Hemerocallis in the lily family, often having grasslike leaves and yellow, orange, or purplish lilylike flowers.
2. East Asian rhizomatous clump-forming perennial herbs having flowers on long leafless stalks; cosmopolitan in cultivation: "day lilies"; sometimes placed in subfamily Hemerocallidaceae.
3. From Greek, hemera, "day" plus kallos, "beauty".