gag

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

• noun Something forced into or put over the mouth to prevent speaking or crying out.
• noun An obstacle to or a censoring of free speech.
• noun A device placed in the mouth to keep it open, as in dentistry.
• noun A practical joke.
• noun A comic effect or remark. synonym: joke.
• noun The act or an instance of gagging or choking.
• intransitive verb To prevent from speaking or crying out by using a gag.
• intransitive verb To stop or restrain from exercising free speech.
• intransitive verb To cause to choke, retch, or undergo a regurgitative spasm.
• intransitive verb To keep (the mouth) open by using a dental gag.
• intransitive verb To block off or obstruct (a pipe or valve, for example).
• intransitive verb To experience a regurgitative spasm in the throat, as from revulsion to a food or smell or in reflexive response to an introduced object.
• intransitive verb To make jokes or quips.

from The Century Dictionary.

• To stop up the mouth or throat of (a person) with some solid body, so as to prevent him from speaking; hence, to silence by authority or by violence; restrain from freedom of speech.
• To pry or keep open by means of a gag.
• To cause to heave with nausea.
• To stop or choke up, as a valve or passage.
• To introduce interpolations into: as, to gag a part.
• To play jokes upon; joke; guy.
• Synonyms Gag, Muzzle, Muffle; stifle. To gag is to silence by thrusting something into the mouth and securing it in place. To muzzle a dog, or other creature having a projecting mouth, is to incase the mouth and nose (muzzle) in a framework called a muzzle, in order to prevent him from biting or eating. Both gag and muzzle are sometimes used figuratively for the act of silencing effectively by moral compulsion, gag implying also roughness or severity in the performance: as, a muzzled press; to gag a public speaker by threats of violence. To muffle is primarily to conceal by wrapping up, but the word has a secondary use to express the deadening of sound, by wrapping (as an oar) or otherwise (as a drum).
• To retch; heave with nausea.
• To interpolate words of one's own into one's part: said of an actor.
• noun Something thrust into the mouth or throat to prevent speech or outcry; hence, any violent or authoritative suppression of freedom of speech.
• noun A mouthful which produces nausea and retching, or threatens with choking.
• noun An apparatus or device for distending the jaws, such as is used in various surgical operations; hence, anything used to pry or keep open the jaws.
• noun In coal-mining, a chip of wood in a sinking pit-bottom or sump.
• noun An interpolation introduced by an actor into his part, whether in accordance with custom or with his own fancy.
• noun A joke, especially a practical joke; a farce; a hoax.
• noun A common name of Mycteroperca microlepis, a large serranoid fish, attaining a length of two or three feet: found on the southern Atlantic and Gulf coasts of the United States.

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

• transitive verb To stop the mouth of, by thrusting sometimes in, so as to hinder speaking; hence, to silence by authority or by violence; not to allow freedom of speech to.
• transitive verb To pry or hold open by means of a gag.
• transitive verb To cause to heave with nausea.
• intransitive verb To heave with nausea; to retch.
• intransitive verb Slang To introduce gags or interpolations. See Gag, n., 3.
• noun Something thrust into the mouth or throat to hinder speaking.
• noun A mouthful that makes one retch; a choking bit.
• noun Slang A speech or phrase interpolated offhand by an actor on the stage in his part as written, usually consisting of some seasonable or local allusion.
• noun (Harness) a rein for drawing the bit upward in the horse's mouth.
• noun (Harness) a loop on the throat latch guiding the gag rein.

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

• abbreviation group specific antigens
• noun A device to restrain speech, such as a rag in the mouth secured with tape or a rubber ball threaded onto a cord or strap.
• noun law An order or rule forbidding discussion of a case or subject.
• noun A joke or other mischievous prank.
• noun A convulsion of the upper digestive tract.
• verb intransitive To experience the vomiting reflex.
• verb this sense?) (U.S. Army, slang) To smoke: to order a recruit to exercise until he "gags" (usually spoken in exaggeration).
• verb transitive To restrain someone's speech by blocking his or her mouth.
• verb transitive, figuratively To restrain someone's speech without using physical means.

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

• noun a humorous anecdote or remark intended to provoke laughter