Etymology: origin unknown
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
4. dunk 2
a. to press into a close or tight position <jam his hat on> b. (1) to cause to become wedged so as to be unworkable <jam 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; especially 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 block, crowd, or bump (a pass receiver) near the line of scrimmage in football 6. to pitch inside to (a batter) • jammer noun II. noun Date: 1805 1. a. an act or instance of jamming b. a crowded mass that impedes or blocks <a traffic jam> 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 jam> 4. jam session 5. dunk shot 6. slang a musical piece III. noun Etymology: probably from 1jam Date: circa 1736 a food made by boiling fruit and sugar to a thick consistency • jammy adjective
New Collegiate Dictionary. 2001.