jet

Definitions

General English

Astronomy

  • Outward projection observed springing from some active galaxies and quasars. Jets are thought to be crucial to the processes by which active galactic nuclei emit large amounts of radiation in many wavelengths, and to quasar energy production. They are especially conspicuous in radio galaxies.

Aviation

  • noun a strong fast stream of fluid forced out of an opening
  • noun a type of engine used to power modern aircraft which takes in air at the front, mixes it with fuel, burns the mixture and the resulting expansion of gases provides thrust
  • noun a type of aircraft which has jet engines

Cars & Driving

  • noun a precision-made hole to control the flow of petrol, air or air/fuel mixture, as in a carburettor
  • noun the nozzle containing such a hole

Construction

  • A high-velocity, pressurized stream of fluid or mixture of fluid and air, as emitted from a nozzle or other small orifice.
  • An orifice or other feature of a toilet that starts the siphon action by directing water into the trapway.

Military

  • noun a stream of fire, gas or water sent out under high pressure

Slang

  • verb to depart, leave. A vogue term in black street argot and white campus slang since the 1990s. The word has been used figuratively to mean ‘run fast’ since the 1950s. A variety of euphemisms (like its contemporaries bail, bill, book and jam) for ‘run away’ are essential to the argot of gang members and their playground imitators.

Travel

  • verb to travel by jet

Origin & History of “jet”

English has two distinct words jet. The older, which denotes a type of black stone used in jewellery (14th c.), comes via Old French jaiet and Latin gagātēs from Greek gagā́tēs, which denoted ‘stone from Gagai’, a town in Lycia, in Asia minor, where it was found.

The jet of ‘jet engines’ (16th c.) 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 (16th c.), 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).
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