Etymology 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 uncertain origin; probably originally onomatopoeic. The "performance" sense is first attested with regards to jazz in 1929, and its origin, though uncertain, is likely metaphorical, "something sweet made by the combination of many things", with influence from jamboree.
To get something stuck, often (though not necessarily) in a confined space.
My foot got jammed in a gap between the rocks.
Her poor little baby toe got jammed in the door.
2 more examples
I jammed the top knuckle of my ring finger.
The Ship, which by its Building was Spanish, stuck fast, jaum’d in between two Rocks; all the Stern and Quarter of her was beaten to Pieces with the Sea […]1719 May 6 (Gregorian calendar), [Daniel Defoe], The Life and Strange Surprizing Adventures of Robinson Crusoe, […], 3rd edition, London: […] W[illiam] Taylor […], published 1719, →OCLC, page 226:
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To brusquely force something into a space; to cram, to squeeze.
They temporarily stopped the gas tank leak by jamming a piece of taffy into the hole.
The rush-hour train was jammed with commuters.
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Jamm’d in at midnight, in cold winter weather,1779, George Colman, Farewell Epilogue, spoken at Wynnstay after the representation of Cymbeline and The Spanish Barber, 22 January, 1779, in Prose on Several Occasions: Accompanied with Some Pieces in Verse, London: T. Cadel, 1787, Volume 3, p. 283, Since the new post-horse tax, I dare engage That some folks here have travell’d in the Stage
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To render something unable to move.
Considering the results of the CFD wind simulation, the NTSB designed several series of static and dynamic elevator load tests to determine what conditions, consistent with the known circumstances of the accident, could enable the inboard actuating crank and links of the right elevator's geared tab to move beyond their normal range of travel and become locked in an overcenter position (and, as a result, jam the right elevator).2019 February 14, National Transportation Safety Board, “2.3.3 Elevator Load Testing”, in Aircraft Accident Report: Runway Overrun During Rejected Takeoff, Ameristar Air Cargo, Inc., dba Ameristar Charters, flight 9363, Boeing MD-83, N786TW, Ypsilanti, Michigan, March 8, 2017, archived from the original on 02 Jul 2022, page 56:
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To cause congestion or blockage. Often used with "up".
A single accident can jam the roads for hours.
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To block or confuse a radio or radar signal by transmitting a more-powerful signal on the same frequency.
The government jams foreign propaganda broadcasts.
The airstrike suffered minimal casualties because electronic-warfare aircraft were jamming the enemy air-defense radars.
Entertainment, Lifestyle, Music To play music (especially improvisation as a group, or an informal unrehearsed session).
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To injure a finger or toe by sudden compression of the digit's tip.
When he tripped on the step he jammed his toe.
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To attempt to score points.
Toughie jammed four times in the second period.
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Nautical, Transport To bring (a vessel) so close to the wind that half her upper sails are laid aback.
It won't do to jam her,” answered Stone ;" but it might be worth findin' out if th' Hope won't lie closer than t' other can." Half a point ----"(Can we date this quote?), William Clark Russell, The Golden Hope:
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Canada, Informal To give up on a date or some other joint endeavour; to stand up, chicken out, jam out.
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Colloquial To be of high quality (especially for music).
UK, Informal A household that is only barely able to meet its financial obligations.
Well, technically, a Jam is a working-class Brexit voter who feels alienated by the creeping march of globalisation.2016 November 20, “Jam – the new government acronym ‘just about managing’ to make sense”, in The Guardian:
Although most of the income for JAM families comes from work, it is, in many cases, topped up by welfare support.2019 February 13, Tahir Maher, “Just About Managing (JAM)”, in Liberal Democrat Voice:
jam
noun
Etymology 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 uncertain origin; probably originally onomatopoeic. The "performance" sense is first attested with regards to jazz in 1929, and its origin, though uncertain, is likely metaphorical, "something sweet made by the combination of many things", with influence from jamboree.
Uncommon, In the US A sweet mixture of fruit boiled with sugar and allowed to congeal. Often spread on bread or toast or used in jam tarts
He is allergic to jam.
She loves eating jam for breakfast in hotels.
2
A difficult situation.
It's a blackmail ring, and the district attorneys get a share of the loot. […] Well, they got him in the same kind of jam, and soaked him to the tune of three hundred and eighty-six thousand.1928, Upton Sinclair, Boston:
She was married when we first met / Soon to be divorced / I helped her out of a jam, I guess / But I used a little too much force1975, Bob Dylan, “Tangled Up in Blue”:
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Where, where is my common sense? / How did I get in a jam like this?1977, David Byrne, “Uh-Oh, Love Comes to Town”, in Talking Heads: 77, performed by Talking Heads:
The pitcher's in a jam now, having walked the bases loaded with the cleanup hitter coming to bat.
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A blockage, congestion, or immobilization.
a jam on the 101 South, blocking the two right lanes [radio report]
a jam of logs in a river
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According to Boeing, in the history of this elevator design (which exists on all Boeing DC-9/MD-80 series and 717 model airplanes), this accident was the first notification that Boeing had received of an elevator jam occurring on an airplane exposed to ground gusts lower than 65 kts. Boeing noted that the elevator design first entered service in 1965 on the then-Douglas DC-9 airplane.2019 February 14, National Transportation Safety Board, “1.3.2.3 Elevator Design Standard for Ground Gust Loads”, in Aircraft Accident Report: Runway Overrun During Rejected Takeoff, Ameristar Air Cargo, Inc., dba Ameristar Charters, flight 9363, Boeing MD-83, N786TW, Ypsilanti, Michigan, March 8, 2017, archived from the original on 02 Jul 2022, page 12:
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Entertainment, Lifestyle, MusicCommon An informal, impromptu performance or rehearsal.
And a mix CD titled "Summer Jamz 2000." Jamz is spelled with a "z".2025, S.E. Case, chapter 1, in Rigsby WI, volume 1: Foothold, →ISBN, retrieved 23 Aug 2025, page 16:
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The result is an outstanding assortment of sophisticated, sexy and hip-hop-tinged R&B grooves, ballads and party jams.2001, Jet, volume 100, number 22, page 25:
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Broadly An informal event where people brainstorm and collaborate on projects.
We came up with some new ideas at the game jam.
[…] a day at new Farm Park with an art jam, fursuit games, and a nerf war, ending in the evening at the strike Wintergarden bowling center.2017, Fred Patten, Furry Fandom Conventions, 1989-2015, page 92:
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Slang That which one particularly prefers, desires, enjoys, or cares about.
Slang Sexual relations or the contemplation of them.
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Slang Something enjoyable; a delightful situation or outcome.
’Tis fine to be a pretty girl, or just a gay and witty girl, And obviously to be both is rightly counted jam, But even more desirable, and clearly less acquirable, Is that mysterious quality denominated glam.1939 July 19, The Bulletin, Sydney, page 14, column 1:
Etymology Borrowed from Persian جامه (“garment”) and/or Hindustani (Hindi जामा (jāmā) / Urdu جامہ (jāma)), meaning "garment, robe". Related to pajamas and pyjamas.