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