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."

Definitions of flea
  1. noun
    any wingless bloodsucking parasitic insect noted for ability to leap
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    Pulex irritans
    the most common flea attacking humans
    Ctenocephalides canis, dog flea
    flea that attacks dogs and cats
    Ctenocephalides felis, cat flea
    flea that breeds chiefly on cats and dogs and rats
    Tunga penetrans, chigger, chigoe, chigoe flea
    small tropical flea; the fertile female burrows under the skin of the host including humans
    Echidnophaga gallinacea, sticktight, sticktight flea
    parasitic on especially the heads of chickens
    type of:
    ectoparasite, ectozoan, ectozoon, epizoan, epizoon
    any external parasitic organism (as fleas)
    small air-breathing arthropod
Word Family

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