The highest point.
The point, in any trajectory of an object in space, where it is farthest from the Earth.
The point, in an orbit about the Earth, that is farthest from the Earth: the apoapsis of an Earth orbiter.
The point, in an orbit about any planet, that is farthest from the planet: the apoapsis of any satellite.
A crowning achievement, culmination or finishing touch.
Any of the stones making up the top layer of a wall; a coping stone.
To complete as a crowning achievement; to top off.
To train in the Capstone Military Leadership Program.