'Ragweed' definitions:

Definition of 'ragweed'

(from WordNet)
noun
Widespread European weed having yellow daisylike flowers; sometimes an obnoxious weed and toxic to cattle if consumed in quantity [syn: ragwort, tansy ragwort, ragweed, benweed, Senecio jacobaea]
noun
Any of numerous chiefly North American weedy plants constituting the genus Ambrosia that produce highly allergenic pollen responsible for much hay fever and asthma [syn: ragweed, ambrosia, bitterweed]

Definition of 'Ragweed'

From: GCIDE
  • Ragweed \Rag"weed`\ (r[a^]g"w[=e]d`), n. (Bot.) A common American composite weed (Ambrosia artemisiaefolia) with finely divided leaves; hogweed. [1913 Webster]
  • Great ragweed, a coarse American herb (Ambrosia trifida), with rough three-lobed opposite leaves. [1913 Webster]