jam in WordNet English dictionary

1. interfere with or prevent the reception of signals
   "Jam the Voice of America"; "block the signals emitted by this station"
   jam  block 
   
2. block passage through
   "obstruct the path"
   obstruct  obturate  impede  occlude  jam  block  close up 
   
3. crowd or pack to capacity
   "the theater was jampacked"
   jam  jampack  ram  chock up  cram  wad 
   
4. crush or bruise
   "jam a toe"
   jam  crush 
   
5. get stuck and immobilized
   "the mechanism jammed"
   jam 
   
6. press tightly together or cram
   "The crowd packed the auditorium"
   throng  mob  pack  pile  jam 
   
7. push down forcibly
   "The driver jammed the brake pedal to the floor"
   jam 
   

1. a dense crowd of people
   crush  jam  press 
   
2. deliberate radiation or reflection of electromagnetic energy for the purpose of disrupting enemy use of electronic devices or systems
   jamming  electronic jamming  jam 
   
3. informal terms for a difficult situation
   "he got into a terrible fix"; "he made a muddle of his marriage"
   fix  hole  jam  mess  muddle  pickle  kettle of fish 
   
4. preserve of crushed fruit
   jam