Plain English Meaning
A qualified mechanic who is licensed by the FAA to work on aircraft and sign off that the work was done correctly.
Full Definition
An FAA-certificated technician trained and authorized to inspect, service, repair, and approve aircraft and aircraft components for return to service. AMTs typically hold an Airframe rating, a Powerplant rating, or both (commonly called an A&P), issued under 14 CFR Part 65.
Context Anchor
Pilots encounter this term when discussing aircraft condition, , , repairs, and about whether an aircraft should fly.