jam

{{11}}jam (n.¹) "fruit preserve," 1730s, probably a special use of JAM (Cf. jam) (v.) with a sense of "crush fruit into a preserve."

{{12}}jam (n.²) "a tight pressing between two surfaces," 1806, from JAM (Cf. 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.

{{12}}jam (v.) "to press tightly," also "to become wedged," 1706, of unknown origin, perhaps a variant of CHAMP (Cf. 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.