Plain English Meaning
It is an FAA approval to fly an aircraft that does not qualify for a regular airworthiness certificate. The aircraft is allowed to fly, but only for certain purposes and under specific rules tied to its category.
Full Definition
An FAA-issued airworthiness certificate granted to aircraft that do not meet the requirements for a standard airworthiness certificate. It authorizes operation under specific limitations and is issued in categories such as primary, restricted, limited, light-sport, experimental, and provisional, each with its own permitted uses and operating restrictions.
Context Anchor
Seen in aircraft certification, aircraft documents, preflight paperwork, and discussions of whether an aircraft is legal to fly for a particular purpose.