To jam is to squeeze something tightly into a space, the way your friends might jam themselves into your tiny car.

You might have to jam an extra row of books onto your bookshelf when you run out of room. Another way to jam is to get stuck, and a jam can be a dense bunch of stuck people or things, like a traffic jam. If you play a musical instrument, you might jam, or casually improvise, with other musicians. And of course the jam you spread on your toast is a delicious, sweet fruit preserve.

Definitions of jam
  1. verb
    press tightly together or cram
    synonyms: mob, pack, pile, throng
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    type of:
    crowd, crowd together
    to gather together in large numbers
  2. verb
    crowd or pack to capacity
    synonyms: chock up, cram, jampack, ram, wad
    put something somewhere so that the space is completely filled
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    type of:
    cram into a cavity
  3. verb
    push down forcibly
    “The driver jammed the brake pedal to the floor”
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    type of:
    force, push
    move with force
  4. verb
    crush or bruise
    jam a toe”
    synonyms: crush
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    type of:
    bruise, contuse
    injure the underlying soft tissue or bone of
  5. verb
    get stuck and immobilized
    “the mechanism jammed
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    type of:
    malfunction, misfunction
    fail to function or function improperly
  6. noun
    a dense crowd of people
    synonyms: crush, press
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    snarl-up, traffic jam
    a number of vehicles blocking one another until they can scarcely move
    a traffic jam so bad that no movement is possible
    type of:
    a large number of things or people considered together
  7. noun
    informal terms for a difficult situation
    synonyms: fix, hole, kettle of fish, mess, muddle, pickle
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    dog's breakfast, dog's dinner
    a poor job; a mess
    type of:
    a condition or state of affairs almost beyond one's ability to deal with and requiring great effort to bear or overcome
  8. verb
    block passage through
    synonyms: block, close up, impede, obstruct, obturate, occlude
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    disengage, free
    free or remove obstruction from
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    block off, blockade
    obstruct access to
    barricade, barricado
    block off with barricades
    prevent access to by barricading
    asphyxiate, choke, stifle, suffocate
    impair the respiration of or obstruct the air passage of
    tie up
    restrain from moving or operating normally
    dam, dam up
    obstruct with, or as if with, a dam
    block out, screen
    prevent from entering
    earth up, land up
    block with earth, as after a landslide
    bar, barricade, block, block off, block up, blockade, stop
    render unsuitable for passage
    back up, choke, choke off, clog, clog up, congest, foul
    become or cause to become obstructed
    gum up
    stick together as if with gum
    block off, close off, shut off
    block off the passage through
    protect from light, heat, or view
    bar access to
    crap up
    become obstructed or chocked up
    block, choke up, lug, stuff
    silt, silt up
    become chocked with silt
    type of:
    hinder, impede
    be a hindrance or obstacle to
  9. verb
    interfere with or prevent the reception of signals
    Jam the Voice of America”
    synonyms: block
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    barrage jam
    jam an entire frequency spectrum
    point jam
    jam a narrow band of frequencies
    spot jam
    jam a single frequency
    blanket jam
    jam a broad spectrum of frequencies to affect all communications in the area except for directional antenna communications
    type of:
    break up, cut off, disrupt, interrupt
    make a break in
  10. noun
    deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
    synonyms: electronic jamming, jamming
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    barrage jamming
    electronic jamming over a wide range of frequencies simultaneously
    selective jamming, spot jamming
    electronic jamming of a specific channel or frequency
    type of:
    ECM, electronic countermeasures
    electronic warfare undertaken to prevent or reduce an enemy's effective use of the electromagnetic spectrum
  11. noun
    preserve of crushed fruit
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    strawberry jam, strawberry preserves
    made with strawberries
    type of:
    conserve, conserves, preserve, preserves
    fruit preserved by cooking with sugar
  12. verb
    play music with a group informally or in an improvised way
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    type of:
    play on an instrument
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