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.

Primary Meanings of jam

press tightly together or cram
a dense crowd of people
block passage through
deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
preserve of crushed fruit
Full Definitions of jam

v press tightly together or cram

mob, pack, pile, throng
Type of:
crowd, crowd together
to gather together in large numbers

v crowd or pack to capacity

chock up, cram, jampack, ram, wad
put something somewhere so that the space is completely filled
Type of:
cram into a cavity

v push down forcibly

“The driver jammed the brake pedal to the floor”
Type of:
force, push
move with force, "He pushed the table into a corner"

v crush or bruise

jam a toe”
Type of:
bruise, contuse
injure the underlying soft tissue or bone of

v get stuck and immobilized

“the mechanism jammed
Type of:
malfunction, misfunction
fail to function or function improperly

n a dense crowd of people

crush, press
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

n informal terms for a difficult situation

fix, hole, kettle of fish, mess, muddle, pickle
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

v block passage through

block, close up, impede, obstruct, obturate, occlude
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

v interfere with or prevent the reception of signals

Jam the Voice of America”
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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

n deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems

electronic jamming, jamming
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

n preserve of crushed fruit

strawberry jam, strawberry preserves
made with strawberries
Type of:
conserve, conserves, preserve, preserves
fruit preserved by cooking with sugar

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