any of various plants belonging to the genus Trillium, native to eastern North America, of the lily family, as T. erectum, having rank-smelling purple, yellow, or white flowers.
tril·li·um (trĭl'ē-əm) n. Any of various plants of the genus Trillium, of North America, the Himalaya Mountains, and eastern Asia, usually having a cluster of three leaves and a variously colored, three-petaled flower. Also called birthroot, wake-robin.
[New Latin Trillium, genus name, probably from Swedish trilling, triplet (from its three leaves), from obsolete Swedish tri, three, from Old Swedish thrīr; see trei- in Indo-European roots.]