Jet has a number of meanings. See:

• Jet, a stream of fluid that can be mathematically characterized
• Jet engine
• Jet aircraft
• Jet (slang)
• jet (lignite), a mineral
• JET (Japan Exchange and Teaching) program
• In mathematics, a jet bundle or spray (mathematics).
• Jet, a rock band from Melbourne, Australia
• Blue jet, a form of upper atmospheric lightning
• Jet (comic)
• Jet Magazine
• JET (Joint European Torus), a fusion reactor
• JET TV, a television station used in Jadeworld
• In astrophysics a "relativistic jet" is a powerful plasma emitted from an Active Galaxy
• "Jet" was the name of a hit rock music single on the 1973 Band on the Run album by Wings.