[jam] vb jammed ; jam.ming [origin unknown] vi (1706) 1 a: to become blocked or wedged b: to become unworkable through the jamming of a movable part
2: to force one's way into a restricted space
3: to take part in a jam session ~ vt 1 a: to press into a close or tight position "~ his hat on" b (1): to cause to become wedged so as to be unworkable "~ the typewriter keys" (2): to make unworkable by jamming c: to block passage of: obstruct d: to fill often to excess: pack "the crowd jammed the theater"
2: to push forcibly; esp: to apply (brakes) suddenly and forcibly--used with on
3: crush, bruise
4. a: to make unintelligible by sending out interfering signals or messages b: to make (as a radar apparatus) ineffective by jamming signals or by causing reflection of radar waves
5: to pitch inside to (a batter) -- jam.mer n
[2]jam n (1805) 1 a: an act or instance of jamming b: a crowded mass that impedes or blocks "a traffic ~"
2. a: the quality or state of being jammed b: the pressure or congestion of a crowd: crush
3: a difficult state of affairs: fix "got into a ~"
4: jam session
5: dunk shot [3]jam n [prob. fr. [1]jam] (ca. 1736): a food made by boiling fruit and sugar to a thick consistency -- jam.my adj