horizon
/hə-ˈrī-zᵊn/
noun
the line where the earth seems to meet the sky : the apparent junction of earth and sky
the great circle on the celestial sphere formed by the intersection of the celestial sphere with a plane tangent to the earth's surface at an observer's position
range of perception or experience
sailing toward the horizon
noun
the uppermost dark-colored layer of a soil consisting largely of partly disintegrated organic debris
noun
a gyroscopic flight instrument designed to indicate aircraft attitude with respect to the true horizon