pyrethrum
noun
py·re·thrum
pī-ˈrē-thrəm 
-ˈre-
-ˈre-
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)
Examples of pyrethrum in a Sentence
Recent Examples on the Web
Having hit the global market it was abandoned during the 1980s due to the pyrethrum crisis but Fusco documents the journey of this flower and its market return under the Kenyan government in an ambitious attempt to help farmers meet the growing global demand for organic products.
—
Joanne Shurvell, Forbes, 15 Apr. 2021
In 1807, chemists isolated pyrethrum from an Armenian daisy.
—Carl Zimmer, Discover Magazine, 4 May 2010
To observe pyrethrum’s effects, Dong and her colleagues attached tiny electrodes to hairs on mosquitoes’ antennae.
—Rachel Nuwer, Scientific American, 19 July 2021
Do not use pyrethrum products for these or any other pests.
—Howard Garrett, Dallas News, 26 July 2021
Lives can be spared by applying insect repellents, including a chrysanthemum flower extract called pyrethrum that humans have used for thousands of years.
—Rachel Nuwer, Scientific American, 19 July 2021
During the 1980s, the pyrethrum crisis began, instigated by the chemical synthesis of pyrethroids that led to the manufacturing of cheaper but non-organic products.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
The pyrethrum is known as the ‘flower of death’ – a nickname that neatly describes this delicate daisy imbued with murderous power.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
The pyrethrum is cultivated mainly in the hills of Nakuru in Kenya and is the arch foe of the insect world.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
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Joanne Shurvell, Forbes, 15 Apr. 2021
In 1807, chemists isolated pyrethrum from an Armenian daisy.
—Carl Zimmer, Discover Magazine, 4 May 2010
To observe pyrethrum’s effects, Dong and her colleagues attached tiny electrodes to hairs on mosquitoes’ antennae.
—Rachel Nuwer, Scientific American, 19 July 2021
Do not use pyrethrum products for these or any other pests.
—Howard Garrett, Dallas News, 26 July 2021
Lives can be spared by applying insect repellents, including a chrysanthemum flower extract called pyrethrum that humans have used for thousands of years.
—Rachel Nuwer, Scientific American, 19 July 2021
During the 1980s, the pyrethrum crisis began, instigated by the chemical synthesis of pyrethroids that led to the manufacturing of cheaper but non-organic products.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
The pyrethrum is known as the ‘flower of death’ – a nickname that neatly describes this delicate daisy imbued with murderous power.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
The pyrethrum is cultivated mainly in the hills of Nakuru in Kenya and is the arch foe of the insect world.
—Cecilia Rodriguez, Forbes, 4 Mar. 2021
Cite this Entry
“Pyrethrum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pyrethrum. Accessed 12 Jul. 2025.
Copy CitationKids Definition
pyrethrum
noun
py·re·thrum
pī-ˈrē-thrəm
-ˈreth-rəm
-ˈreth-rəm
1
: any of several chrysanthemums that have finely divided leaves and include ornamental plants as well as important sources of insecticides
2
: an insecticide consisting of the dried heads of some Old World pyrethrums
Medical Definition
pyrethrum
noun
py·re·thrum
pī-ˈrē-thrəm
-ˈreth-rəm
-ˈreth-rəm
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)
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