Plant of the thistle or aster family

• Any plant of the genus Ageratum having opposite leaves and small heads of blue or white flowers
• Border bloomer in a garden
• Rhizomatous plant of central and southeastern United States and West Indies having large showy heads of clear blue flowers
• Sometimes placed in genus Eupatorium
• Border plant
• Garden flower

Wiktionary Word definitions in Wiktionary
n. (context uncountable English) Any of the genus (taxlink Ageratum genus noshow=1) of tropical American herbs, annuals and perennials, from the sunflower family Asteraceae, tribe Eupatorieae; they are sometimes used in floral displays.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Ageratum \A*ger"a*tum\ ([.a]*j[e^]r"[.a]*t[u^]m or [a^]j`[~e]r*[=a]"t[u^]m), prop. n. [NL., fr. Gr. 'agh`raton a sort of plant; 'a priv. + gh`ras old age.] (Bot.) A genus of plants, one species of which ( Ageratum Mexicanum ) has lavender-blue ...

WordNet Word definitions in WordNet
n. rhizomatous plant of central and southeastern United States and West Indies having large showy heads of clear blue flowers; sometimes placed in genus Eupatorium [syn: mistflower , mist-flower , Conoclinium coelestinum , Eupatorium coelestinum ] any plant ...

Wikipedia Word definitions in Wikipedia
Ageratum , ( whiteweed in the USA), is a genus of 40 to 60 tropical and warm temperate flowering annuals and perennials from the family Asteraceae, tribe Eupatorieae. Most species are native to Central America and Mexico but four are native to the United ...