| common ragweed | (n) annual weed with finely divided foliage and spikes of green flowers; common in North America; introduced elsewhere accidentally, Syn. Ambrosia artemisiifolia |
| great ragweed | (n) a coarse annual with some leaves deeply and palmately three-cleft or five-cleft, Syn. Ambrosia trifida |
| ragweed | (n) 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. bitterweed, ambrosia |
| ragweed pollen | (n) pollen of the ragweed plant is a common allergen |
| western ragweed | (n) coarse perennial ragweed with creeping roots of dry barren lands of southwestern United States and Mexico, Syn. Ambrosia psilostachya, perennial ragweed |
| burweed marsh elder | (n) tall annual marsh elder common in moist rich soil in central North America that can cause contact dermatitis; produces much pollen that is a major cause of hay fever, Syn. Iva xanthifolia, false ragweed |
| ragwort | (n) widespread European weed having yellow daisylike flowers; sometimes an obnoxious weed and toxic to cattle if consumed in quantity, Syn. Senecio jacobaea, benweed, ragweed, tansy ragwort |
