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

As climate change delays the first winter frosts across much of North America, summer ragweed also keeps flowering longer, extending the latter part of pollen season into the fall, said David Wees, a faculty lecturer in horticulture at McGill University in Montreal. —Keerti Gopal, ArsTechnica, 8 May 2026

These plants include ragweed, daisies, marigolds and chrysanthemums. —Bestreviews, Chicago Tribune, 14 Apr. 2026

Tree pollen is the first culprit to start causing symptoms, followed by grass pollination later in the spring and summer and ragweed in the late summer and fall. —Joe Mutascio, IndyStar, 1 Apr. 2026

Spring allergies are usually triggered by tree and grass pollen, while fall allergies are often caused by ragweed. —Trisha Easto, USA Today, 24 Mar. 2026

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