apex

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.

Source: Webster's Revised Unabridged Dictionary (1913), United States public domain. See methodology for full licensing detail. Word validity for game play may differ from any official game dictionary.