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).

\ \ Cf.⇒ INJECT, JETSAM, JETTISON, JETTY, JUT, PROJECT, REJECT, SUBJECT