ragweed

noun

rag·​weed ˈrag-ˌwēd 

: any of various chiefly North American weedy composite herbs (genus Ambrosia) that produce highly allergenic pollen

Illustration of ragweed

Examples of ragweed in a Sentence

Recent Examples on the Web

Seasonal allergies occur when the immune system interprets certain airborne substances, like ragweed or tree pollen, as a threat and overreacts. —Sarah Cottone, Health, 16 Apr. 2025

Our top allergens right now are ragweed, chenopods and elm. —Megan Stringer, Axios, 16 Sep. 2024

In Europe, projections showed a probable increase in Ambrosia—or ragweed pollen—also linked to rising temperatures. —Jeffrey Kluger, Time, 9 Apr. 2025

Changes to the landscape like urbanization can create a more favorable habitat for plants like ragweed. —Umair Irfan, Wired News, 5 Apr. 2025

Word History

First Known Use

1790, in the meaning defined above

Rhymes for ragweed

• accede
• agreed
• airspeed
• alkyd
• bindweed
• chickweed
• concede
• decreed
• duckweed
• exceed
• flaxseed
• impede

Kids Definition

ragweed

noun

rag·​weed ˈrag-ˌwēd 

: any of various chiefly North American weedy herbs related to the daisies and producing pollen irritating to the eyes and noses of some persons

Medical Definition

ragweed

noun

rag·​weed ˈrag-ˌwēd 

: any of various chiefly North American weedy herbaceous plants comprising the genus Ambrosia and producing highly allergenic pollen responsible for much hay fever and asthma: as

a

: an annual weed (A. artemisiifolia) with finely divided foliage that is common on open or cultivated ground in much of North America

b

: a coarse annual (A. trifida) with some or all of the leaves usually deeply and palmately 3-cleft or 5-cleft

called also great ragweed