Plain English Meaning

Things on the aircraft that don't have to be working for this particular flight to be legal and safe. They can be broken or missing as long as the rules for flying with them inoperative are followed.

Full Definition

Equipment, instruments, or items installed on an aircraft that are not required for the safe operation of the specific flight being conducted under the applicable regulations, aircraft type certificate, and operating conditions. Items in this category may be inoperative for a flight provided the aircraft is operated in accordance with an approved Minimum Equipment List (MEL) or, where no MEL exists, the inoperative equipment provisions of 14 CFR 91.213(d).

Context Anchor

Seen when deciding whether an airplane may be flown with an item that is not working.