Definition
A fuel injector is a device that delivers a metered spray of fuel directly into the intake port of each cylinder, or in some systems directly into the cylinder itself, instead of relying on a carburetor to mix fuel and air in a single central location.
Plain English
It is a small nozzle that squirts a measured amount of fuel into each cylinder so the engine gets the right fuel-to-air mix at every cylinder, every time.
Context Anchor
Seen in discussions of engine fuel systems, diesel-style aircraft engines, and two-stroke compression-ignition engine operation.
Derivation
From Latin 'injicere', meaning 'to throw in'. The injector literally throws (sprays) fuel into the intake stream — a useful image for what the device actually does.
Why Pilots Care
Fuel injectors give precise metering, better high-altitude performance, and eliminate carburetor icing risk compared with float-type systems.
Analogy
A fuel injector is like a fine spray nozzle on a bottle, but built for an engine and controlled much more precisely. It breaks fuel into a spray so it can burn more easily.
Intuition Check
A fuel injector is not the same as a carburetor. A carburetor mixes fuel with air before it enters the engine; a fuel injector delivers fuel directly into the intake airflow or combustion area, depending on the engine design.
Example Sentence 1
Because the aircraft has a fuel injector for each cylinder, there is no carburetor heat control on the panel.
Example Sentence 2
During climb the pilot noticed uneven cylinder temperatures traced to a faulty fuel injector.