Apex

A"pex (?), n.; pl. E. Apexes (?); L. Apices (?). [L.] 1. The tip, top, point, or angular summit of anything; as, the apex of a mountain, spire, or cone; the apex, or tip, of a leaf.

2. (Mining) The end or edge of a vein nearest the surface. [U.S.]

Apex of the earth's motion (Astron.), that point of the heavens toward which the earth is moving in its orbit.