Definition
An airplane powered by two or more engines. In FAA usage, it refers to fixed-wing aircraft with more than one powerplant, which introduces specific handling considerations during normal operations and especially when one engine fails, including asymmetric thrust and altered stall behavior.
Plain English
An airplane with more than one engine.
Context Anchor
Seen in training, operating procedures, and handbook discussions for airplanes that have two or more engines.
Derivation
Multi-' comes from Latin multus, meaning 'many.' So a multiengine airplane is simply one with many (more than one) engines.
Why Pilots Care
Multiengine airplanes behave differently from single-engine airplanes when one engine fails. The remaining engine produces thrust on one side only, which yaws and rolls the airplane and changes stall and control characteristics. Multiengine flying requires its own training and a separate rating.
Intuition Check
Do not read “multi” as meaning a large number of engines. In aviation, a multiengine airplane simply has two or more engines.
Example Sentence 1
Before flying a multiengine airplane solo, the pilot must hold the appropriate multiengine rating on their certificate.
Example Sentence 2
Before the cross-country flight the pilot confirmed that the multiengine airplane met single-engine climb performance requirements.