Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Any of various weeds of the genus Ambrosia of the composite family, having small, greenish, unisexual flower heads and producing abundant pollen that is one of the chief causes of hay fever.
  • noun Chiefly British Ragwort.

from The Century Dictionary.

  • noun Any plant of the composite genus Ambrosia; especially, the common North American species A. trifida, the great ragweed or horse-cane, and A. artemisiæfolia, the Roman wormwood or hogweed.
  • noun The ragwort or St.-James-wort, Senecio Jacobæa.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Bot.) A common American composite weed (Ambrosia artemisiæfolia) with finely divided leaves; hogweed.
  • noun a coarse American herb (Ambrosia trifida), with rough three-lobed opposite leaves.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun A plant of the genus Ambrosia. These weeds are particularly noted for producing pollen which people with hay fever are allergic to.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • 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
  • noun widespread European weed having yellow daisylike flowers; sometimes an obnoxious weed and toxic to cattle if consumed in quantity

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[From the ragged shape of its leaves.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

rag +‎ weed

Examples

  • If you're allergic to other plants, such as ragweed, your risk of an allergic reaction to Calendula may be greater.

    A Flower With Power to Soothe Skin?

  • Old field plant communities are composed primarily of successional species such as ragweed, asters, goldenrod, sumac, wild carrot and various grasses.

    Old Woman Creek National Estuarine Research Reserve, Ohio

  • Since response to allergens such as ragweed occurs quickly not only in the nose but also in the sinuses, "you can try treatment before exposure," he said.

    Medlogs - Recent stories

  • Since response to allergens such as ragweed occurs quickly not only in the nose but also in the sinuses, "you can try treatment before exposure," he said.

    Medlogs - Recent stories

  • Since response to allergens such as ragweed occurs quickly not only in the nose but also in the sinuses, "you can try treatment before exposure," he said.

    Medlogs - Recent stories

  • Since response to allergens such as ragweed occurs quickly not only in the nose but also in the sinuses, "you can try treatment before exposure," he said.

    Medlogs - Recent stories

  • Those who have problems with weeds, such as ragweed, tend to suffer most mid-August to mid-September.

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  • In spring, for example, tree pollens make their presence felt most strongly during morning hours, whereas allergens such as ragweed tend to do their damage in the middle of the day during the fall season.

    Lahontan Valley News - Top Stories

  • Cetirizine Hydrochloride syrup is indicated for the relief of symptoms associated with seasonal allergic rhinitis due to allergens such as ragweed, grass and tree pollens in adults and children 2 years of age and older.

    News Centre@myiris.com India's Most Comprehensive Financial Destination

  • Since response to allergens such as ragweed occurs quickly not only in the nose but also in the sinuses, "you can try treatment before exposure," he said.

    Medlogs - Recent stories

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