Parallel to or in the plane of the horizon.

In anatomy, a plane passing through the standing body. A person lying on a bed is considered in a horizontal position. For a more complete listing of terms used in medicine for spatial orientation, please see the entry to "Anatomic Orientation Terms".

1550s, "relating to or near the horizon," from French horizontal, from Latin horizontem (see horizon). Meaning "flat" (i.e., "parallel to the horizon") is from 1630s. As [..]

parallel to the horizon.

A line with zero slope.

left-right direction or parallel to the Earth and the horizon.

Parallel to the horizon, ground or floor.

Parallel to the horizon, ground or floor. HORMONE

A line with zero slope.

parallel to the horizon, ground or floor.

relating to, directed toward, or consisting of individuals or entities of similar status or on the same level hor·i·zon·tal·ly adv

(n) something that is oriented horizontally(adj) parallel to or in the plane of the horizon or a base line

Lines parallel to the horizon and at right angles to a vertical plane.

in educational management, an arrangement which deals with learners of similar status such as in terms of age/stage: for example, dealing with all of the one year-group rather than involving individua [..]

Pertaining to the horizon. Perpendicular to vertical.

A horizontal line, plane, etc. horizontal beam width. The beam width measured in a horizontal plane.

Moving straight across from side to side rather than up-and-down. For example, the top edge of a piece of paper is horizontal.

tangent to the geoid or parallel to a plane that is tangent to the geoid.

Parallel to the surface of smooth water. In drawings, a line parallel to the top and bottom of the sheet is called horizontal.