Definition of "jargon"

They [the Normans] abandoned their native speech, and adopted the French tongue, in which Latin was the predominant element. They speedily raised their new language to a dignity and importance which it had never before possessed. They found it a barbarous jargon; they fixed it in writing; and they employed it in legislation, in poetry, and in romance.

1849, Thomas Babington Macaulay, chapter I, in The History of England from the Accession of James II, volume I, London: Longman, Brown, Green, and Longmans, page 11

In fact all the competing theories have developed their own specialized jargons and have a tendency to be difficult to penetrate.

2014, Ian Hodder, Archaeological Theory Today

Prussian Trenck, the poor subterranean Baron, jargons and jangles in an unmelodious manner.

1837, Thomas Carlyle, “Fatherland in Danger”, in The French Revolution: A History […], volume III (The Guillotine), London: James Fraser, […], book III (The Girondins), page 184

[T]he noisy jay, / Jargoning like a foreigner at his food; […]

1863 November 23, Henry Wadsworth Longfellow, “The Poet’s Tale. The Birds of Killingworth.”, in Tales of a Wayside Inn, Boston, Mass.: Ticknor and Fields, page 195