flea

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various small, wingless, bloodsucking insects of the order Siphonaptera that are parasitic on mammals and birds and can jump long distances.
• noun Any of various small crustaceans that resemble or move like fleas, such as the water flea.
• idiom (a flea in (one's) ear) An annoying hint or a stinging rebuke.

from The Century Dictionary.

• To clear of fleas.
• noun An insect of the genus Pulex, regarded by entomologists as representing a distinct order Aphaniptera, so called because the wings are inconspicuous scales.
• noun plural The family Pulicidæ, or order Aphaniptera. See these words.
• noun A flea-beetle; a saltatorial beetle of the genus Haltica, as H. nemorum, which injures the turnip, and is also called turnip-flea and turnip-fly.
• noun Any amphipod crustacean which jumps like a flea; a sandhopper; a scud. See beach-flea.
• An obsolete form of flay.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb obsolete To flay.
• noun (Zoöl.) An insect belonging to the genus Pulex, of the order Aphaniptera. Fleas are destitute of wings, but have the power of leaping energetically. The bite is poisonous to most persons. The human flea (Pulex irritans), abundant in Europe, is rare in America, where the dog flea (Ctenocephalides canis, formerly Pulex canis) and the smaller cat flea (Ctenocephalides felis) take its place. See aphaniptera, and dog flea. See Illustration in Appendix.
• noun an unwelcome hint or unexpected reply, annoying like a flea; an irritating repulse; as, to put a flea in one's ear; to go away with a flea in one's ear.
• noun etc. See under Beach, etc.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb Obsolete spelling of flay.
• noun A small, wingless, parasitic insect of the order Siphonaptera, renowned for its bloodsucking habits and jumping abilities.
• noun A thing of no significance.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun any wingless bloodsucking parasitic insect noted for ability to leap