The noun jam has 4 senses (first 1 from tagged texts)
1. (3) jam -- (preserve of crushed fruit)
2. fix, hole, jam, mess, muddle, pickle, kettle of fish -- (informal terms for a difficult situation; "he got into a terrible fix"; "he made a muddle of his marriage")
3. crush, jam, press -- (a dense crowd of people)
4. jamming, electronic jamming, jam -- (deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems)
Overview of verb jam
The verb jam has 7 senses (first 4 from tagged texts)
1. (1) throng, mob, pack, pile, jam -- (press tightly together or cram; "The crowd packed the auditorium")
2. (1) jam -- (push down forcibly; "The driver jammed the brake pedal to the floor")
3. (1) jam, crush -- (crush or bruise; "jam a toe")
4. (1) jam, block -- (interfere with or prevent the reception of signals; "Jam the Voice of America"; "block the signals emitted by this station")
5. jam -- (get stuck and immobilized; "the mechanism jammed")
6. jam, jampack, ram, chock up, cram, wad -- (crowd or pack to capacity; "the theater was jampacked")
7. obstruct, obturate, impede, occlude, jam, block, close up -- (block passage through; "obstruct the path")