Jet

(astronomy) A narrow, elongated feature in the radio or optical map of an active galaxy, quasar, or object in the Milky Way Galaxy, believed to represent an energetic outflow of gas from a compact astronomical object.
(fluid mechanics) A strong, well-defined stream of compressible fluid, either gas or liquid, issuing from an orifice or nozzle or moving in a contracted duct.
(particle physics) A group of particles issuing in approximately the same direction from a high-energy collision of elementary particles, believed to consist of decay products of a member of a quark-antiquark pair created in the collision.

A black, opaque material that takes a high polish. Jet has been used for many centuries for ornamental purposes. It is a compact variety of lignite coal. It has a refractive index of 1.66, a hardness of 3–4 on Mohs scale, and a specific gravity of 1.30–1.35. Jet is compact and durable, and can be carved or even turned on a lathe. The main source is Whitby, England, in hard shales. See also Gem; Lignite.

(Joint Engine Technology) The database engine used in Microsoft Access and that accompanies Visual Basic and C++. Jet is typically used for storing data in the client machine. Developers using Access and Visual Basic access Jet via the DAO/Jet interface, which is a COM object. See DAO.

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