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verb (used with object), jammed, jam·ming.
  1. to press, squeeze, or wedge tightly between bodies or surfaces, so that motion or extrication is made difficult or impossible: The ship was jammed between two rocks.
  2. to bruise or crush by squeezing: She jammed her hand in the door.
  3. to fill too tightly; cram: He jammed the suitcase with clothing.
  4. to press, push, or thrust violently, as into a confined space or against some object: She jammed her foot on the brake.
  5. to fill or block up by crowding; pack or obstruct: Crowds jammed the doors.
  6. to put or place in position with a violent gesture (often followed by on): He jammed his hat on and stalked out of the room.
  7. to make (something) unworkable by causing parts to become stuck, blocked, caught, displaced, etc.: to jam a lock.
  8. Radio.
    1. to interfere with (radio signals or the like) by sending out other signals of approximately the same frequency.
    2. (of radio signals or the like) to interfere with (other signals).
  9. to play (a piece) in a freely improvised, swinging way; jazz up: to jam both standard tunes and the classics.
  10. Nautical. to head (a sailing ship) as nearly as possible into the wind without putting it in stays or putting it wholly aback.
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verb (used without object), jammed, jam·ming.
  1. to become stuck, wedged, fixed, blocked, etc.: This door jams easily.
  2. to press or push, often violently, as into a confined space or against one another: They jammed into the elevator.
  3. (of a machine, part, etc.) to become unworkable, as through the wedging or displacement of a part.
  4. Jazz. to participate in a jam session.
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  1. the act of jamming or the state of being jammed.
  2. a mass of objects, vehicles, etc., jammed together or otherwise unable to move except slowly: a log jam; a traffic jam.
  3. Informal. a difficult or embarrassing situation; fix: He got himself into a jam with his boss.
  4. jam session.
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Origin of jam1

1700–10; apparently imitative; cf. champ1, dam1


  1. a preserve of whole fruit, slightly crushed, boiled with sugar: strawberry jam.
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  1. put on jam, Australian Slang. to adopt a self-important manner or use affected speech.
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Origin of jam2

First recorded in 1720–30; perhaps special use of jam1
Related formsjam·like, jam·my, adjective


  1. Jamaica.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for jam

Contemporary Examples

Historical Examples

  • Treacle, you hear: and for that matter, Martha has no jam to give!

    Night and Morning, Complete

    Edward Bulwer-Lytton

  • You may make a charlotte with any sort of jam, marmalade, or fruit jelly.

  • Before he could recover, the second or tail section of the jam started to pull.

    The Forest

    Stewart Edward White

  • But they ate so much of the bread and butter and jam and cream that they could not eat the cake.

    Changing Winds

    St. John G. Ervine

  • These may be served with jam, treacle, butter and sugar, or with a sweet sauce.

    The Skilful Cook

    Mary Harrison

British Dictionary definitions for jam


verb jams, jamming or jammed
  1. (tr) to cram or wedge into or against somethingto jam paper into an incinerator
  2. (tr) to crowd or packcars jammed the roads
  3. to make or become stuck or lockedthe switch has jammed
  4. (tr often foll by on) to activate suddenly (esp in the phrase jam on the brakes)
  5. (tr) to block; congestto jam the drain with rubbish
  6. (tr) to crush, bruise, or squeeze; smash
  7. radio to prevent the clear reception of (radio communications or radar signals) by transmitting other signals on the same frequency
  8. (intr) slang to play in a jam session
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  1. a crowd or congestion in a confined spacea traffic jam
  2. the act of jamming or the state of being jammed
  3. informal a difficult situation; predicamentto help a friend out of a jam
  4. See jam session
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Derived Formsjammer, noun

Word Origin

C18: probably of imitative origin; compare champ 1


  1. a preserve containing fruit, which has been boiled with sugar until the mixture sets
  2. slang something desirableyou want jam on it
  3. jam today the principle of living for the moment
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Word Origin

C18: perhaps from jam 1 (the act of squeezing)


abbreviation for
  1. Jamaica
  2. Bible James
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for jam


"to press tightly," also "to become wedged," 1706, of unknown origin, perhaps a variant of champ (v.). Of a malfunction in the moving parts of machinery, by 1851. Sense of "cause interference in radio signals" is from 1914. Related: Jammed; jamming. The adverb is recorded from 1825, from the verb.

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"fruit preserve," 1730s, probably a special use of jam (v.) with a sense of "crush fruit into a preserve."

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"a tight pressing between two surfaces," 1806, from jam (v.). Jazz meaning "short, free improvised passage performed by the whole band" dates from 1929, and yielded jam session (1933); but this is perhaps from jam (n.1) in sense of "something sweet, something excellent." Sense of "machine blockage" is from 1890, which probably led to the colloquial meaning "predicament, tight spot," first recorded 1914.

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Online Etymology Dictionary, © 2010 Douglas Harper

jam in Medicine


  1. To block, congest, or clog.
  2. To crush or bruise.
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with jam


see under get in a bind.

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The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.