Definition
An aircraft powered by two or more engines. In pilot certification and training contexts, it specifically refers to airplanes with more than one engine, which require additional training and a separate class rating to operate as pilot in command.
Plain English
An airplane with more than one engine. Flying one requires extra training and a special rating because handling it (especially if an engine fails) is different from flying a single-engine airplane.
Context Anchor
Seen in instrument training when discussing aircraft used for instruction, performance, and procedures that differ from single-engine aircraft.
Derivation
Multi- comes from Latin multus, meaning 'many.' Combined with engine, it simply means 'many engines'—but the aviation usage points to a specific category of aircraft with its own rating and training requirements.
Why Pilots Care
Provides engine redundancy so the aircraft can continue flight and land safely after an engine failure, which is a key safety and training consideration.
Intuition Check
Do not read multiengine as meaning a complicated aircraft or an aircraft with extra electrical systems. Here it simply means the aircraft has two or more engines that provide power for flight.
Example Sentence 1
After earning her private pilot certificate, she began training in a multiengine aircraft to add a multiengine class rating.
Example Sentence 2
Multiengine aircraft must meet specific climb performance standards with one engine inoperative.