[ho.ri.zon] n [ME orizon, fr. LL horizont-, horizon, fr. Gk horizont-, horizon, fr. prp. of horizein to bound, define, fr. horos boundary; perh. akin to L urvum curved part of a plow] (14c) 1 a: the apparent junction of earth and sky b: the great circle on the celestial sphere formed by the intersection of a plane tangent to the earth's surface at an observer's position with the celestial sphere c: range of perception or experience d: something that might be attained "new ~s"
2. a: the geological deposit of a particular time usu. identified by distinctive fossils b: any of the reasonably distinct layers of soil or its underlying material in a vertical section of land c: a cultural area or level of development indicated by separated groups of artifacts -- ho.ri.zon.al adj