flea
Americannoun
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fleas
plural
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any of numerous small, wingless bloodsucking insects of the order Siphonaptera, parasitic upon mammals and birds and noted for their ability to leap.
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either of two common fleas of the genus Ctenocephalides, the very small, black C. felis cat flea or the similar but larger C. canis dog flea, both of which infest cats, dogs, and occasionally humans.
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any of various small beetles and crustaceans that leap like a flea or swim in a jumpy manner, as the water flea and beach flea.
idioms
noun
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any small wingless parasitic blood-sucking insect of the order Siphonaptera , living on the skin of mammals and birds and noted for its power of leaping
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any of various invertebrates that resemble fleas, such as the water flea and flea beetle
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informal a sharp rebuke
Other Word Forms
Noun Inflected Forms
Etymology
Origin of flea
before 900; Middle English fle, Old English flēah, flēa; cognate with German Floh; akin to flee
Explanation
A flea is a tiny biting insect that's especially common on dogs. If you find one flea in your dog's fur, there may be hundreds more hiding in there. Fleas live by sucking blood from a host — they're parasites. You can just barely see a flea with the naked eye, and when you do spot one it may be hopping, since they're known to jump, sometimes from one animal to another. Flea bites are itchy, and fleas can be tricky to get rid of once they've laid eggs on your dog (or in your bed). Some experts think the word's root s the Old English fleon, "to flee."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Visiting the Pochaina flea market 10 days after the Russian attack, AFP journalists could still smell the mix of burnt metal and plastic hanging in the air.
From Barron's ● Aug. 20, 2026
Pet flea treatments should be banned from general sale, a Lords committee has urged, after an inquiry raised concerns about their impact on their environment.
From BBC ● Aug. 5, 2026
The hardworking mother of three daughters called Los Angeles home and collected much of the material for her work from the city’s many flea markets and second hand shops.
From Los Angeles Times ● Jul. 28, 2026
He started selling vintage clothes 11 years ago, when he was 15, switched to kids’ vintage at 20 and has spent the last six years scouring flea markets, websites and swap meets.
From Los Angeles Times ● Jun. 3, 2026
I bathed them and brushed them and helped the visiting vet nurse apply lotion to their over-scratched flea bites.
From "Please Ignore Vera Dietz" by A.S. King
Last month, a park in Fairfax in Marin County was overrun with fleas.
From Los Angeles Times ● Aug. 16, 2026
The cats are all fixed, vaccinated, tested for FIV/Felv, microchipped and treated for fleas and worms.
From Los Angeles Times ● Aug. 10, 2026
Earlier research had indicated that ancient strains of Yersinia pestis lacked some of the genetic features that later allowed bubonic plague to spread efficiently through fleas and rodent hosts.
From Science Daily ● Jun. 18, 2026
Some environmental scientists have flagged two parasiticides found in most spot-on treatments to kill fleas and ticks on cats and dogs, fipronil and imidacloprid, as toxic to wildlife.
From BBC ● Jun. 10, 2026
And there had not been an outbreak of fleas in quite some time.
From "The Interrupted Tale" by Maryrose Wood
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
