subsistence level

: real being : existence

: the condition of remaining in existence : continuation, persistence

: an essential characteristic quality of something that exists

: a device for establishing a horizontal line or plane by means of a bubble in a liquid that shows adjustment to the horizontal by movement to the center of a slightly bowed glass tube

: a measurement of the difference of altitude of two points by means of a level

: horizontal condition

: to make (a line or surface) horizontal : make flat or level

: to bring to a horizontal aiming position

: aim, direct

: having no part higher than another : conforming to the curvature of the liquid parts of the earth's surface

: parallel with the plane of the horizon : horizontal

: even or unvarying in height