horizontal >> hɒrɪˈzɒnt(ə)l
Definition: [adjective] parallel to the plane of the horizon; at right angles to the vertical.
Example: a horizontal line
Definition: [adjective] being at or involving the same level of a hierarchy.
Example: horizontal class loyalties
Definition: [adjective] of or at the horizon.
Example: the horizontal moon
Definition: [noun] a horizontal line, plane, etc.