Definition
In aviation and electrical/mechanical contexts, a descriptor meaning inoperative, non-functioning, or carrying no energy. A dead circuit has no electrical current flowing in it; a dead engine is not running; a dead control is one that produces no response when moved.
Plain English
Not working, not running, or not powered. If something is described as dead, it is producing no output and showing no signs of activity.
Context Anchor
Seen in cockpit reports, maintenance troubleshooting, electrical-system discussions, and engine-operation checks.
Derivation
Dead comes from Old English words meaning lifeless or without life. In aviation, the idea is extended from a living thing to a machine or circuit: it has no useful activity, power, or output.
Why Pilots Care
Knowing whether a system is truly dead -- versus simply quiet or idle -- changes the response. A dead engine in flight means a forced landing; a dead radio means lost communications and a switch to backup procedures.
Intuition Check
Dead does not usually mean broken forever. In aviation, it means the item is not producing useful power, signal, or operation right now.
Example Sentence 1
After the alternator failed, the battery slowly went dead and the avionics shut down one by one.
Example Sentence 2
Preflight checks revealed a dead battery that needed replacement.