Plain English Meaning
A required written history of every inspection and repair done on the aircraft, signed by the mechanic who did the work. The pilot reviews it before flight to confirm the aircraft is legal and safe to fly.
Full Definition
An official record kept for an aircraft (and separately for its engine and propeller) documenting all inspections, repairs, alterations, airworthiness directives complied with, and other maintenance actions performed, along with the date, aircraft total time, and the signature and certificate number of the person returning the aircraft to service.
Context Anchor
A pilot may review the maintenance logbook during to confirm the is legal and in for safe flight.