Definition
An aircraft whose major portion has been fabricated and assembled by a person or persons who undertook the construction project solely for their own education or recreation. The FAA certificates these aircraft in the Experimental category under 14 CFR Part 21.191(g), and they are subject to specific operating limitations that differ from standard-category aircraft.
Plain English
A plane built mostly by a private individual at home, for the fun of building it or to learn from the project, rather than by a manufacturer on a production line.
Context Anchor
Seen in aircraft certification, maintenance records, inspections, and operating-limit discussions.
Derivation
Amateur comes from the Latin amator, meaning lover -- someone who does an activity out of love or interest rather than for pay. In this term it points to the builder's motivation: personal education or enjoyment, not commercial production.
Why Pilots Care
Affects certification rules, operating limitations, maintenance privileges, and inspection requirements.
Intuition Check
Do not read “amateur-built” as “poorly built.” In FAA use, it describes how and why the aircraft was built, not whether it is safe or unsafe.
Example Sentence 1
The mechanic checked the operating limitations before performing work on the amateur-built aircraft, since its inspection requirements differed from a standard-category airplane.
Example Sentence 2
An amateur-built aircraft must meet FAA construction standards and receive a final inspection before flight.