flea
Americannoun
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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:
Ecological consultant Matthew Shardlow said he believed the active ingredients in flea treatments are so toxic, and so easily transferred onto humans, household items, and into water, that they should be withdrawn from sale.
From BBC ● Jun. 10, 2026
The industry body representing flea treatment companies defended the use of preventive flea treatments as important for animal health.
From BBC ● Jun. 10, 2026
Jersey Water said there was no evidence pet and flea treatments were present in the supply.
From BBC ● May 3, 2026
I personally source all my vintage pieces, so I try to visit flea markets every week.
From Los Angeles Times ● Apr. 3, 2026
She makes outfits from the flea market look good on her.
From "I Am Not Your Perfect Mexican Daughter" by Erika L. Sánchez
Scott: We did a nice dinner down by the beach, and everyone got bit by the sand fleas that weren’t supposed to be there.
From The Wall Street Journal ● Apr. 6, 2026
Often, people are exposed to the disease when infected fleas are carried indoors on pets or other animals.
From Los Angeles Times ● Apr. 3, 2026
"Each animal is going to have different circumstances and be at different risk of picking up fleas, for example it depends on the weather, whether your cat goes outside and so on," Rees said.
From BBC ● Mar. 10, 2026
Isoxazolines are designed to kill fleas and ticks, but when treated animals eliminate the drugs, other insects may also be exposed.
From Science Daily ● Feb. 22, 2026
Men and women scrambling down hemp ladders, dangling and dropping like fleas jumping from a dog, plummeting into the increasing surf.
From "Ship Breaker" by Paolo Bacigalupi
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.
