n. The circle which at sea forms the apparent boundary between sea and sky, and on land would bound the sky were all terrestrial obstructions down to the sea-level removed. Called the apparent, sensible, or visible horizon, in distinction from the astronomical horizon (which see, below).n. Hence The line that bounds the view; the limit of vision.n. Figuratively, the limit of intellectual perception, of experience, or of knowledge.n. In geology, a stratum or group of strata characterized by the presence of a particular fossil not found in the underlying or overlying beds, or of a peculiar assemblage of fossils.n. In zoology and anatomy, a level or horizontal line or surface: as, the horizon of the teeth; the horizon of the diaphragmTo limit or bound by a horizon.