Jam meaning : A sweet mixture of fruit boiled with sugar and allowed to congeal. Often spread on bread or toast or used in jam tarts. A difficult situation. Blockage, congestion. An informal, impromptu performance or rehearsal. (by extension) A song; a track. (by extension) An informal event where people brainstorm and collaborate on projects. To get something stuck in a confined space. To brusquely force something into a space; cram, squeeze. To cause congestion or blockage. Often used with "up" To block or confuse a broadcast signal. To throw a pitch at or near the batter's hands. To play music (especially improvisation as a group, or an informal unrehearsed session). To injure a finger or toe by sudden compression of the digit's tip. To attempt to score points. To bring (a vessel) so close to the wind that half her upper sails are laid aback. To give up on a date or some joint endeavour; stand up, chicken out, jam out.