ˌajəˈrād.əm, -ātəm noun
Etymology: New Latin, from Latin ageraton, a plant, from Greek agēraton, from neuter of agēratos ageless, from a- a- (II) + -gēratos (from gēras old age) — more at geriatrics
1. capitalized : a genus of tropical American herbs (family Compositae) having opposite leaves and small heads of blue or white flowers in terminal cymes
2. -s : a plant of the genus Ageratum (especially A. houstonianum )
3. -s : any of several blue-flowered plants of the genus Eupatorium