jamming

Concise Oxford English Dictionary © 2008 Oxford University Press:
jam1

▶verb (jams, jamming, jammed)

• 1 squeeze or pack tightly into a space.

  ■ push roughly and forcibly into a position.

  ■ crowd on to (a road or area) so as to block it.

• 2 become or make unable to move or work due to a part becoming stuck.

• 3 (jam something on) apply something forcibly: he jammed on the brakes.

• 4 make (a radio transmission) unintelligible by causing interference.

• 5 informal (in jazz or blues) improvise with other musicians.

▶noun

• 1 an instance of jamming.

• 2 informal an awkward situation or predicament: I'm in a jam.

• 3 Climbing a handhold obtained by jamming a part of the body into a crack in the rock.

• 4 informal an improvised performance by a group of musicians, especially in jazz or blues.

– derivatives
jammer noun.

– origin C18: prob. symbolic; cf. jag1 and cram.

Concise Oxford English Dictionary © 2008 Oxford University Press:
jam2

▶noun

• 1 chiefly Brit. a spread or conserve made from fruit and sugar.

• 2 Brit. something easy or pleasant.

▶verb (jam, jamming, jammed) make (fruit) into jam.

– phrases
jam tomorrow a desirable thing that is promised but rarely materializes. [phr. from Lewis Carroll's Through the Looking Glass (1871).]

– origin C18: perh. from jam1.