Plain English Meaning
A landing approach where everything is set up correctly and stays that way: the right path down to the runway, the right speed, the right descent rate, gear and flaps in the correct position, and the right power setting. Once stabilized, the pilot only needs small adjustments to keep it that way until touchdown.
Full Definition
An approach to landing in which the airplane is established on the proper flightpath, at the proper airspeed, descent rate, and configuration, with engine power set appropriately, and only minor corrections required to maintain those to the .