Meaning of HORIZON in English
1》 the line at which the earth's surface and the sky appear to meet.
↘(also apparent ~ ) this line represented as a circle, ignoring irregularities and obstructions.
↘(also true ~ ) Astronomy a great circle of the celestial sphere, the plane of which passes through the centre of the earth and is parallel to that of the apparent ~.
2》 the limit of a person's knowledge, experience, or interest.
3》 Geology & Archaeology a layer or level of soil or rock with particular characteristics or representing a particular period.
on the ~ imminent.
ME: via OFr. from late L. ~ , from Gk horizōn (kuklos) 'limiting (circle)'.
Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004