The outermost layer or boundary of an object or area. The surface of the table was smooth and polished.
The outward appearance or aspect of something, often as distinct from its true nature. Beneath the surface of his calm demeanor, he was very anxious.
The flat, uppermost part of a body of water. The ducks were gliding across the surface of the pond.
A continuous set of points that has length and breadth but no thickness, often used in mathematics. In geometry, a plane is considered a flat surface.