flatsurface
nounUK /ˌflæt ˈsɜːfɪs/
US /ˌflæt ˈsɝːfɪs/
A flat surface is a smooth, even area that does not go up or down.
The table has a flat surface, so the ball stays still on it.
OTHER MEANINGS
2. In geometry, a perfectly even two-dimensional area with no curves or bumps.
The teacher drew a triangle on the flat surface of the paper.
3. A calm, unvarying condition or situation without sudden changes.
After the storm, the sea returned to a flat surface.
4. The smooth face of a tool or object used for spreading or pressing.
She spread the butter with the flat surface of the knife.