Plain English Meaning
The standard height pilots fly when circling the airport to land. At most airports, that means flying 1,000 feet above the ground around the airport, then descending from there as you turn toward the runway.
Full Definition
The specified altitude at which aircraft fly the airport traffic pattern, typically 1,000 feet above airport elevation for propeller-driven aircraft, unless established otherwise for a particular airport. It is flown on the downwind leg and serves as the reference altitude from which the descent to landing is begun.
Context Anchor
Used when entering, flying, or leaving the airport traffic pattern, especially at non-towered airports or when reviewing before .