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"to press tightly," also "to become wedged," 1706, of unknown origin, perhaps a variant of champ (v.). Of a malfunction in the moving parts of machinery, by 1851. Sense of "cause interference in radio signals" is from 1914. Related: Jammed; jamming. The adverb is recorded from 1825, from the verb.
"fruit preserve," 1730s, probably a special use of jam (v.) with a sense of "crush fruit into a preserve."
"a tight pressing between two surfaces," 1806, from jam (v.). Jazz meaning "short, free improvised passage performed by the whole band" dates from 1929, and yielded jam session (1933); but this is perhaps from jam (n.1) in sense of "something sweet, something excellent." Sense of "machine blockage" is from 1890, which probably led to the colloquial meaning "predicament, tight spot," first recorded 1914.
v. jammed, jam·ming, jams
To block, congest, or clog.
To crush or bruise.
: Jam bands do have stylesnoun
[all senses have some relation to the asi notion of squeezing or crushing so as to make jam]
A heterosexual man
[1970s+ Homosexuals; said to be fr just a man]
in electronics, broadcasting a strong signal that overrides or obscures a target signal. Jamming of radio and television stations broadcasting from beyond borders may be carried out by a country that does not wish its citizens to receive programs from abroad. In military activities, jamming is frequently employed to confuse enemy radar or communications. The techniques of jamming are many and varied, but most of them simply consist of broadcasting a powerful radio signal, modulated with noise, on the precise frequency of the signal being jammed.