Definition
A mechanical failure in which two moving parts bind together and stop moving relative to each other, usually because lubrication has failed and friction has welded or galled the surfaces. A seized engine is one whose internal components have locked up and can no longer rotate.
Plain English
When metal parts that should slide or spin against each other get so hot or dry that they jam solid and stop moving.
Context Anchor
Seen in engine, propeller, wheel, brake, and maintenance discussions when a part that should move freely becomes stuck or locked.
Derivation
From Old French 'seisir' meaning 'to take hold of' or 'grab.' In mechanical use, the parts have effectively grabbed onto each other and refuse to let go.
Why Pilots Care
An engine seizure produces immediate and total loss of thrust, leaving the pilot with only seconds to establish best glide and select a landing site.
Analogy
It is like a jar lid that is so stuck it will not turn, except in an aircraft the stuck part may be part of an engine, wheel, or control system.
Intuition Check
Do not read seize here as “grab” or “take by force.” In aviation maintenance, it means a mechanical part has become stuck or locked and can no longer move normally.
Example Sentence 1
After oil pressure dropped to zero, the engine seized within minutes and the pilot executed a forced landing.
Example Sentence 2
After the oil leak, the cylinders began to seize and the propeller stopped turning.