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late 14c., "basket in which fish are caught or carried," from Medieval Latin iuncata "rush basket," perhaps from Latin iuncus "rush." Shifted meaning by 1520s to "feast, banquet," probably via notion of a picnic basket, which led to extended sense of "pleasure trip" (1814), and then to "tour by government official at public expense for no discernable public benefit" (by 1886, American English). Cf. Italian cognate giuncata "cream cheese" (originally made in a rush basket), a sense of junket also found in Middle English and preserved lately in dialects.
A tour undertaken by a government official at public expense and often for no public benefit: An agricultural junket through nine European countries (1886+)verb
: junketed like contemporary tourists
[fr junket, ''feast; merrymaking,'' found by 1530 and of obscure origin; the verb is found by 1821, meaning ''take a pleasure trip,'' without the US political sense]