jetyoudaoicibaDictYouDict[jet 词源字典]
jet: English has two distinct words jet. The older, which denotes a type of black stone used in jewellery [14], comes via Old French jaiet and Latin gagātēs from Greek gagátēs, which denoted ‘stone from Gagai’, a town in Lycia, in Asia Minor, where it was found. The jet of ‘jet engines’ [16] goes back ultimately to a word that meant ‘throw’ – Latin jacere (from which English also gets inject, project, reject, etc).

A derivative of this was jactāre, which also meant ‘throw’. It passed via Vulgar Latin *jectāre into Old French as jeter, and when English took it over it was originally used for ‘protrude, stick out’: ‘the houses jetting over aloft like the poops of ships, to shadow the streets’, George Sandys, Travels 1615. This sense is perhaps best preserved in jetty ‘projecting pier’, and in the variant form jut [16], while the underlying meaning ‘throw’ is still present in jettison ‘throw things overboard’ and its contracted form jetsam.

But back with the verb jet, in the 17th century it began to be used for ‘spurt out in a forceful stream’. The notion of using such a stream to create forward motion was first encapsulated in the term jet propulsion in the mid 19th century, but it did not take concrete form for nearly a hundred years (the term jet engine is not recorded until 1943).
=> inject, jetsam, jettison, jetty, jut, project, reject, subject[jet etymology, jet origin, 英语词源]
jet (n.1)youdaoicibaDictYouDict
"stream of water," 1690s, from French jet, from jeter (see jet (v.)). Sense of "spout or nozzle for emitting water, gas, fuel, etc." is from 1825. Hence jet propulsion (1867) and the noun meaning "airplane driven by jet propulsion" (1944, from jet engine, 1943). The first one to be in service was the German Messerschmitt Me 262. Jet stream is from 1947. Jet set first attested 1951, slightly before jet commuter plane flights began. Jet age is attested from 1952.
jet (v.)youdaoicibaDictYouDict
early 15c., "to prance, strut, swagger," from Middle French jeter "to throw, thrust," from Late Latin iectare, abstracted from deiectare, proiectare, etc., in place of Latin iactare "toss about," frequentative of iacere "to throw, cast," from PIE root *ye- "to do" (cognates: Greek iemi, ienai "to send, throw;" Hittite ijami "I make"). Meaning "to sprout or spurt forth" is from 1690s. Related: Jetted; jetting.
jet (n.2)youdaoicibaDictYouDict
"deep black lignite," mid-14c., from Anglo-French geet, Old French jaiet "jet, lignite" (12c.), from Latin gagates, from Greek gagates lithos "stone of Gages," town and river in Lycia. As "a deep black color," also as an adjective, attested from mid-15c.