Plain English Meaning
Registration is the FAA paperwork that says who owns the aircraft and gives it its tail number. A copy of this certificate has to be in the aircraft whenever it's flown.
Full Definition
The official record, issued by the FAA, that identifies the legal owner of a specific aircraft and assigns it a unique N-number. The Certificate of Aircraft Registration must be carried aboard the aircraft during operation in the United States.
Context Anchor
Pilots encounter registration when checking the required aircraft documents before flight, usually along with the airworthiness certificate and other onboard records.
Derivation
Registration comes from words meaning “to enter in a record or list.” That helps here because aircraft registration is not just a label on the airplane; it is an official entry in FAA records.
Why Pilots Care
An aircraft cannot be legally flown in the United States until it has valid registration.