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:
Mom would go to garage sales and flea markets to buy them.
From The Wall Street Journal ● Sep. 29, 2026
And Berlin’s flea markets are always worth exploring.
From The Wall Street Journal ● Sep. 17, 2026
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
When she was eventually rescued, she had lost lots of fur because of a severe flea infestation and was underweight.
From BBC ● Jul. 1, 2026
Instead, with a frown, she spits on her finger and rubs at the reddish brown spots—dried blood from flea bites I scratch too much—that speckle the sleeves of my dirty white blouse.
From "The Queen of Water" by Laura Resau
It’s caused by a bacteria called Yersinia pestis that infects fleas and the small mammals that host fleas, and there are actually three types of plague depending on which part of the body becomes infected.
From Slate ● Oct. 8, 2026
Humans usually contract it from fleas that have fed on infected wild rodents, or sometimes by handling the tissue or body fluids of a diseased animal, according to the U.S.
From The Wall Street Journal ● Oct. 6, 2026
Flea-borne typhus is an acute febrile bacterial infection caused by Rickettsia Typhi bacteria, which is spread by infected fleas often found on pets and wildlife.
From Los Angeles Times ● Sep. 24, 2026
A clergyman I met at Reagan National Airport recently told me that our world is as filled with corruption as a Latin American animal shelter is filled with fleas.
From Salon ● Sep. 18, 2026
The free ride may be provided by mosquitoes, fleas, lice, or tsetse flies that spread malaria, plague, typhus, or sleeping sickness, respectively.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
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.
