Meaning of HORIZON in English
In general, the apparent or visible junction of the Earth and sky, as seen from any specific position. Also called the apparent, visible, or local horizon. A horizontal plane passing through a point of vision or perspective center. The apparent or visible horizon approximates the true horizon only when the point of vision is very close to sea level.
DOD English dictionary of military terms. Английский словарь военных терминов DOD. 2012