jam1

verb (jams, jamming, jammed)

• 1 [with object] squeeze or pack tightly into a specified space:four of us were jammed in one compartment people jammed their belongings into cars [no object]:75,000 refugees jammed into a stadium today to denounce the accord
• push (something) roughly and forcibly into position or a space:he jammed his hat on
• crowd onto (a road) so as to block it:the roads were jammed with traffic
• cause (telephone lines) to be continuously busy with a large number of calls:listeners jammed WBOQ’s switchboard with calls

• 2become or make unable to move or work due to a part seizing or becoming stuck: [no object]:the photocopier jammed [with object]:the doors were jammed open
• [with object] make (a broadcast or other electronic signal) unintelligible by causing interference:GPS signals are weak and easily jammed

• 3 [no object] informal improvise with other musicians, especially in jazz or blues:the opportunity to jam with Atlanta blues musicians

noun

• 1an instance of a machine or thing seizing or becoming stuck:paper jams
• informal an awkward situation or predicament:I’m in a jam
• short for traffic jam.
• [often with adjective] Climbing a handhold obtained by stuffing a part of the body such as a hand or foot into a crack in the rock.

• 2 (also jam session) an informal gathering of musicians improvising together, especially in jazz or blues.