nearhorizontal

Nearhorizontal is an adjective describing something oriented almost horizontally, i.e., lying close to the local horizon. The term implies a small angle relative to the horizontal plane; the exact threshold varies by discipline.

In surveying and navigation, a nearhorizontal line of sight or elevation is close to zero degrees. In aviation, a nearhorizontal attitude or flight path denotes level flight with only a slight climb or descent.

In astronomy and atmospheric science, near-horizontal conditions refer to rays or observations with a small elevation angle, such as light near the horizon at sunrise or sunset when elevation angles are low. In geology and engineering, near-horizontal often characterizes rock cuts, strata, or boreholes that are close to parallel with the ground surface; near-horizontal drilling is a standard term describing wells drilled with a small inclination relative to the surface to maximize contact with a reservoir.

Measurement typically uses pitch or elevation angle from the horizontal plane. The practical boundary between nearhorizontal and strictly horizontal is context dependent, and may be defined as within a few degrees, often on the order of 0–5 or 0–10 degrees.

Related terms include horizontal, slightly inclined, shallow-angle, and tangential orientation. The term is generally informal and used across technical fields to convey an orientation that is close to, but not exactly, horizontal.