pyrethrum

play

noun py·re·thrum \ pī-ˈrē-thrəm , -ˈre- \

Definition of pyrethrum

1 :any of several chrysanthemums with finely divided often aromatic leaves including ornamentals as well as important sources of insecticides

2 :an insecticide made from the dried heads of any of several Old World chrysanthemums (especially Chrysanthemum cinerariaefolium)

See pyrethrum defined for kids

Recent Examples of pyrethrum from the Web

Nymphs can be controlled with insecticidal soap, pyrethrum, rotenone or neem.

— ellen nibali, baltimoresun.com, "Garden Q&A: Black-eyed Susans with fungal leaf spot disease," 11 July 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'pyrethrum.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of pyrethrum

Latin, pellitory, from Greek pyrethron, from pyr fire

NEW! Time Traveler

First Known Use: circa 1543

See Words from the same year

Medical Dictionary

pyrethrum

play

noun py·re·thrum \ pī-ˈrē-thrəm , -ˈreth-rəm \

medical Definition of pyrethrum

1 :any of several chrysanthemums with finely divided often aromatic leaves including ornamentals as well as important sources of insecticides

2 :an insecticide consisting of or derived from the dried heads of any of several Old World chrysanthemums (genus Chrysanthemum of the family Compositae)