Plain English Meaning
A list that tells you which broken or missing items on your airplane you can still fly with, and under what conditions. If something is broken and it isn't on this list as allowed, the airplane cannot legally fly until it's fixed.
Full Definition
An FAA-approved document, specific to a particular aircraft, that lists the instruments and equipment that may be inoperative while still permitting the aircraft to be flown legally and safely under defined conditions and limitations.
Context Anchor
Pilots encounter the MEL during preflight, after a maintenance issue is found, or after a rejected takeoff when deciding whether the airplane can legally and safely depart again.
Derivation
The name describes itself only in part. 'Minimum' here doesn't mean 'the least amount of equipment' — it means the minimum that must still be working for flight to be permitted. Everything not on the list must be operational.