From Longman Dictionary of Contemporary Englishjamjam1 /dʒæm/ ●●● S3 noun 1 
food [countable, uncountable]DFF a thick sweet substance made from boiled fruit and sugar, eaten especially on bread → jelly strawberry jam a jam sandwich jam jars2 cars/people [countable]MOVE/CHANGE POSITION a situation in which it is difficult or impossible to move because there are so many cars or people Sorry we’re late. We got stuck in a traffic jam.3 machine [countable] a situation in which a machine does not work because something is stopping a part from moving It caused a jam in the printer.4 difficult situation [countable usually singular] informal a difficult situation(be/get) in/out of/into a jam We became friends after he helped me out of a jam.5 music [countable] a) a jam session b) a song or piece of music, especially one by a rap or rock group 6 → kick out the jams7 → jam tomorrow
food [countable, uncountable]DFF a thick sweet substance made from boiled fruit and sugar, eaten especially on bread → jelly strawberry jam a jam sandwich jam jars2 cars/people [countable]MOVE/CHANGE POSITION a situation in which it is difficult or impossible to move because there are so many cars or people Sorry we’re late. We got stuck in a traffic jam.3 machine [countable] a situation in which a machine does not work because something is stopping a part from moving It caused a jam in the printer.4 difficult situation [countable usually singular] informal a difficult situation(be/get) in/out of/into a jam We became friends after he helped me out of a jam.5 music [countable] a) a jam session b) a song or piece of music, especially one by a rap or rock group 6 → kick out the jams7 → jam tomorrowExamples from the Corpus
jam• a jam in the copy machine• In case we don't like the cake she brings half a tea-chest of biscuits and three different jams.• Initial press reports on the Dec. 20 accident focused on how pilot errors got the crew into a navigational jam.• By the time she's cleared the jam, they're in the outskirts of Bournemouth.• What Case can not promise his members is immediate respite from the jams.• Otherwise every traffic jam will gradually vanish beneath a rising tide of its own foamy output.• Streets around the normally tranquil town of Morton in Marsh were sealed and long traffic jams built up.traffic jam• By the time we reached the Red Fort we had hit a traffic jam.• The Columbia River was a traffic jam of barges carrying bauxite to the smelters in Longview, Washington.• Otherwise every traffic jam will gradually vanish beneath a rising tide of its own foamy output.• Just look at these cabins, and you forget traffic jams, mortgages and mayhem back home.• Streets around the normally tranquil town of Morton in Marsh were sealed and long traffic jams built up.• That figure is arrived at by multiplying the total length of traffic jams by their duration.• You arrive just in time for a rolling traffic jam in a town crammed with shops, apartments and construction cranes.• Nevertheless, telecommuting is destined to increase, he said, pushed along by snowstorms, traffic jams and technological progress.(be/get) in/out of/into a jam• At first he appeared to be relieved to be helped out of a jam.jamjam2 ●●○ verb (jammed, jamming) 1 push hard [transitive always + adverb/preposition]PUSH to push something somewhere using a lot of force, until it can move no further He jammed his foot on the accelerator and the car sped off. A chair had been jammed up against the door.2 machine [intransitive, transitive] (also jam up)BREAKBROKEN if a moving part of something jams, or if you jam it, it no longer works properly because something is preventing it from moving The front roller has jammed on the photocopier.3 block [intransitive, transitive] (also jam up)PREVENT if a lot of people or vehicles jam a place, they fill it so that it is difficult to move SYN cram Crowds jammed the entrance to the stadium.jam into They all jammed into the car. → jammed(2)4 music [intransitive] (also jam out)APM to play music in an informal way with other people → jam session5 → jam on the brakes6 → jam somebody’s/the switchboard7 radio [transitive]TCBPREVENT to deliberately prevent broadcasts or other electronic signals from being received, by broadcasting signals on the same wavelength8 → somebody is jamming → jam out→ See Verb tableExamples from the Corpus
jam• The third time the clasp jammed.• One pilot reported that his controls had jammed.• Some guys are getting together tonight at Scott's to jam.• Just hold the door open while I jam a wedge under it.• The electronic equipment jams enemy radar signals.• All five boys jammed happily into the back seat.• Mark jams his under a cushion.• Bollards are prone to sudden collapse, and the ropes often jam in the groove behind the capstan during retrieval.• In his desperation to escape, he fumbled the lever and the door jammed partly open.• All-night jam sessions were common in Kansas City jazz clubs of the 1930s.• Kelly poured himself another glass of wine and jammed the cork back into the bottle.• Crowds of supporters jammed the lobby.• The result was the Yosemite that tourists see today, jammed with awe-inspiring plutons with rounded tops and steep, vertical sides.• Matthews used to jam with drummer Carter Beauford and saxophonist LeRoi Moore.• We were jamming with J.D. and Rich last night.• Of course, the newspapers were filled with it, and the docks, railyards, and whorehouses were jammed with soldiers.Origin jam2 (1700-1800) Perhaps copying the action 