from The American Heritage® Dictionary of the English Language, 4th Edition

  • transitive v. To drive or wedge forcibly into a tight position: jammed the cork in the bottle.
  • transitive v. To activate or apply (a brake) suddenly. Often used with on: jammed the brakes on.
  • transitive v. To cause (moving parts, for example) to lock into an unworkable position: jammed the typewriter keys.
  • transitive v. To pack (items, for example) to excess; cram: jammed my clothes into the suitcase.
  • transitive v. To fill (a container or space) to overflowing: I jammed the suitcase with clothes. Fans jammed the hallway after the concert.
  • transitive v. To block, congest, or clog: a drain that was jammed by debris.
  • transitive v. To crush or bruise: jam a finger.
  • transitive v. Electronics To interfere with or prevent the clear reception of (broadcast signals) by electronic means.
  • transitive v. Baseball To throw an inside pitch to (a batter), especially to prevent the batter from hitting the ball with the thicker part of the bat.
  • intransitive v. To become wedged or stuck.
  • intransitive v. To become inoperable: The computer keyboard jammed.
  • intransitive v. To force one's way into or through a limited space.
  • intransitive v. Music To participate in a jam session.
  • intransitive v. Basketball To make a dunk shot.
  • n. The act of jamming or the condition of being jammed.
  • n. A crush or congestion of people or things in a limited space: a traffic jam.
  • n. A trying situation. See Synonyms at predicament.
  • n. A preserve made from whole fruit boiled to a pulp with sugar.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A sweet mixture of fruit boiled with sugar and allowed to congeal. Often spread on bread or toast or used in jam tarts.
  • n. A difficult situation.
  • n. Blockage, congestion.
  • n. (popular music) An informal, impromptu performance or rehearsal.
  • n. (baseball) A difficult situation for a pitcher or defending team.
  • n. (basketball) A forceful dunk.
  • n. (roller derby) A play during which points can be scored.
  • n. Any of several rock-climbing maneuvers requiring wedging of an extremity into a tight space.
  • n. luck.
  • v. To get something stuck in a confined space.
  • v. To brusquely force something into a space; cram, squeeze.
  • v. To cause congestion or blockage. Often used with "up"
  • v. To block or confuse a broadcast signal.
  • v. To throw a pitch at or near the batter's hands.
  • v. To play music (especially improvisation as a group.)
  • v. To injure a finger or toe by sudden compression of the digit's tip.
  • v. To attempt to score points.

from the GNU version of the Collaborative International Dictionary of English

  • n. A kind of frock for children.
  • n. See jamb.
  • n. A mass of people or objects crowded together; also, the pressure from a crowd; a crush
  • n. An injury caused by jamming.
  • n. A difficult situation.
  • n. A preserve of fruit boiled with sugar and water; also called jelly
  • intransitive v. To become stuck so as not to function.
  • intransitive v. To play an instrument in a jam session.
  • intransitive v. To crowd together; -- usually used with together or in.
  • transitive v. To press into a close or tight position; to crowd; to squeeze; to wedge in; to cram.
  • transitive v. To crush or bruise.
  • transitive v. To bring (a vessel) so close to the wind that half her upper sails are laid aback.
  • transitive v. To block or obstruct by packing too much (people or objects) into.
  • transitive v. To interfere with (a radio signal) by sending other signals of the same or nearby frequency.
  • transitive v. To cause to become nonfunctional by putting something in that blocks the movement of a part or parts.

from The Century Dictionary and Cyclopedia

  • To press; squeeze; thrust or press down or in with force or violence; thrust or squeeze in so as to stick fast; press or crowd in such a manner as to prevent motion or hinder extrication.
  • To fill full; block up; prevent the movement of by pressure, crowding, etc.
  • To tread hard or make firm by treading, as land is trodden hard by cattle.
  • To become wedged together or in place, as by violent impact; stick fast: as, the door jams.
  • To push (a bill or measure) through the regular routine of a legislative body by the brute force of a majority controlled by ‘the machine,’ without proper consideration or discussion. [Political slang.]
  • To smear or spread with jam: as, a slice of bread thickly jammed.
  • To become jam; thicken to the consistency of jam.
  • n. A crush; a squeeze; pressure by thrusting or crowding.
  • n. A crowd of objects irregularly and tightly pressed together by arrest of their movement; a block, as of people, vehicles, or floating logs.
  • n. A conserve of fruits prepared by boiling them to a pulp in water with sugar.
  • n. Another spelling of jamb, 4.
  • n. An extra pool in the game of napoleon.
  • n. The title of certain native chiefs in northwestern India.
  • n. In England, a kind of dress worn by children: so called from the Hindu jama, a long muslin gown worn in India by both Mohammedans and Hindus.
  • n. An abbreviation of Jamaica.

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

  • v. crush or bruise
  • v. crowd or pack to capacity
  • n. informal terms for a difficult situation
  • n. deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
  • v. press tightly together or cram
  • v. get stuck and immobilized
  • n. a dense crowd of people
  • v. push down forcibly
  • v. interfere with or prevent the reception of signals
  • v. block passage through
  • n. preserve of crushed fruit


from The American Heritage® Dictionary of the English Language, 4th Edition

Origin unknown.
Possibly from jam1.


  • The term jam-eating comes from when people worked in the mines.

    Whitehaven News headlines

  • With the term jam band incorporating everything from blues to bluegrass these days, it's an overused handle that barely describes all the disparate bands lumped within its parameters.

    Broward-Palm Beach New Times | Complete Issue

  • NOW, to celebrate this release, the SMD boys, some of their musical friends, and our pals at Modular UK are throwing a party TONIGHT in London - SMD will be there along with the Klaxons, Mystery Jets, Good Books, and the Modular and Ten Dead Sloanes DJ crews - the jam is at Sin (144 Charing Cross Road - WC2H 0LB) and costs six pounds in advance or eight with your student union card.

    I'm a hustler baby (Music (For Robots))

  • One is the - there's not a sufficient amount of what we call jam sessions.

    A Jazz Guitar Legend: Alive, Live and 75

  • We'd do what we called jam-but the only guy who could hold his instrument right side up was Peter Van Gelder.

    Grace Slick The Biography

  • There was no explicit support for radical group Hamas, though a small group of demonstrators made a shout using a pun with the Spanish word jamás ( "never"), whose pronunciation is nearly identical to "Hamas". Directorio y Buscador de Blogs Latinos

  • Since this "jam" is getting a little dated, a number of the pictures posted there have already gone the way of the dodo bird.

    Archive 2010-02-01

  • The cause of the "jam" is a prevalence of south winds for a few days, and then a sudden change to the north -- the first forcing the ice down the Upper Lakes into the river, which is prevented by the north-winds from getting into Lake Ontario.

    Ice Bridge at Niagara.

  • Bacon jam is excellent on slices of tomatoes, plopped on a warm biscuit, stirred into a bowl of beans or spread on top of a cheeseburger.

    make it at home | Homesick Texan

  • Apricot jam is one of my favorites and I especially enjoy eating it on peanut butter toast!

    How to make apricot jam | Homesick Texan


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  • "Wireless Teleg. To render (wireless signals) unintelligible by sending out from another instrument other (meaningless) signals or wave impulses."

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