Altitude has multiple uses depending on the context in which it's used (aviation, geometry, geographical survey, sport, and more). As a general definition, altitude's a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context. Vertical distance measurements in the "down" direction are commonly referred to as depth. Altitude in aviation In aviation, the term altitude can have… (More on Altitude)