Definition of ageratum
: any of a genus (Ageratum) of annual tropical American composite herbs often cultivated for their small showy heads of usually blue or white flowers; also : a related blue-flowered perennial (Eupatorium coelestinum)
Origin and Etymology of ageratum
New Latin, genus name, from Greek agēratos ageless, from a- + gēras old age — more at geront-
First Known Use: circa 1737
Seen and Heard
What made you want to look up ageratum? Please tell us where you read or heard it (including the quote, if possible).