A plane tangential to the level surface at a point is called?

A plane tangential to the level surface at a point is called?

کسی مقام پر سطح کی سطح پر ٹینجینٹل ہوائی جہاز کہلاتا ہے؟
Explanation

 It just touches the level surface at one point.

Perpendicular to the vertical (plumb line) at that point.

Used in geodesy and mapping for local approximations of Earth's surface.