Definition
An airplane powered by two engines, typically mounted one on each wing or arranged in a push-pull configuration on the fuselage centerline. A twin-engine airplane is designed so that flight can be continued, under defined conditions, if one engine fails.
Plain English
An airplane with two engines instead of one. If one quits, the other can still keep the airplane flying, within limits.
Context Anchor
Seen in multiengine training, aircraft performance discussions, and emergency procedures for engine failure, especially at low airspeed or low altitude.
Derivation
Twin' simply means two of something matched as a pair. The term highlights that the two engines are a matched set working together, not just any two engines bolted on.
Why Pilots Care
Provides redundancy so the airplane can continue flight and land safely after an engine failure, but demands training to manage asymmetric thrust and higher decision speeds.
Intuition Check
Do not assume “twin-engine” means the airplane can always keep climbing if one engine quits. It only means the airplane has two engines; performance after losing one depends on weight, speed, altitude, configuration, and pilot control.
Example Sentence 1
The pilot transitioned from a single-engine trainer to a twin-engine airplane and began practicing engine-out procedures.
Example Sentence 2
Before takeoff the instructor reviewed the accelerate-stop distance for the twin-engine airplane in case an engine failed on the runway.