Other forms: jams, jamming, jammed
Jam is fruit boiled with sugar until it sets thick enough to spread. A spoonful on hot toast, the red layer through the middle of a sponge cake, the jar at the back of the fridge with a sticky ring under it.
The other jam is about things pressed into too small a space, and it is everywhere: a traffic jam, a jammed printer, a drawer jammed shut, a hall jam-packed with people. You jam your foot on the brake and jam a chair under the door handle. If you are in a jam, you are in trouble you cannot easily get out of. Musicians took the word as well — a jam session is people playing together with nothing written down, and they jam for hours. Two notes for travellers: British jam with pieces of fruit in it is close to what Americans call preserves, and American jelly is the clear, seedless kind.
1nounjamFruit boiled with sugar until it sets, spread on bread and used in cakes.~14%
“She spread jam thickly on the last piece of toast.”
synonyms: preserve
2verbforceTo force something into a space that is too small for it.~2%
“He jammed the last shirt into the case and sat on the lid.”
3verbbecomeTo become stuck and stop working.~14%
“The printer jams every time you load thick paper.”
4nounmassA mass of people or vehicles packed so tightly that nothing moves.~28%
“We sat in a jam outside the tunnel for forty minutes.”
5verbblockTo block a radio signal or broadcast on purpose.~14%
“The army jammed the local stations before dawn.”
6nounsessionAn informal session of musicians playing together with nothing written down.~28%
“Sunday night is an open jam at the pub on the corner.”
Shares are an estimate: a language model read 7 sentences found in the wild and placed 7 of them on a sense — a count of our sample, not a measurement of English.
Jam first appears in the early 1700s as a verb — to press, to be wedged in. A dialect relative, jammock, meant to squeeze something into a soft pulp, which is close to what happens in the pan. It may reach back to Middle English chammen or champen, to bite and gnash the teeth, the noisy family that also gave champ and chomp, probably an imitation of the sound. The music sense arrives with jazz in 1929; nobody knows why, though 'something sweet made by mixing many things' and a nudge from jamboree are the usual guesses.
First attested in the early 18th c. as a verb meaning “to press, be pressed, be wedged in”. Compare dialectal jammock (“to press, squeeze, crush into a soft mass, chew food"; also "a soft, pulpy substance”). Perhaps from Middle English chammen, champen "to bite upon something, gnash the teeth"; whence modern champ, chomp, of unknown origin; probably originally imitative of the sound. The "performance" sense is first attested with regards to jazz in 1929, and its origin, though unknown, is likely metaphorical, "something sweet made by the combination of many things", with influence from jamboree.
Etymology from Wiktionary, CC BY-SA