at right angles to the vertical; parallel to the earth's surface plane of the horizon; level
at or near the horizon
the horizontal moon
said of a mechanism: having the main part lying or working in the horizontal plane, as is the piston in a horizontal engine
relating to people or positions of the same status in a hierarchy; compare vertical1
horizontal promotion
applying uniformly to all members of a group
a horizontal bonus
said of a merger: combining businesses involved in the same kind or stage of production
horizontality /-ʹtaliti/ noun
horizontally adv