The Collaborative International Dictionary of English v.0.48:
Jet \Jet\, n. [F. jet, OF. get, giet, L. jactus a throwing, a
throw, fr. jacere to throw. Cf. Abject, Ejaculate,
Gist, Jess, Jut.]
1. A shooting forth; a spouting; a spurt; a sudden rush or
gush, as of water from a pipe, or of flame from an
orifice; also, that which issues in a jet.
2. Drift; scope; range, as of an argument. [Obs.]
3. The sprue of a type, which is broken from it when the type
is cold. --Knight.
Jet propeller (Naut.), a device for propelling vessels by
means of a forcible jet of water ejected from the vessel,
as by a centrifugal pump.
Jet pump, a device in which a small jet of steam, air,
water, or other fluid, in rapid motion, lifts or otherwise
moves, by its impulse, a larger quantity of the fluid with
which it mingles.