surface

England's method of attacking batting is going to be tested on what is expected to be a lively surface at Perth Stadium.

"But under the surface, we were beginning to sense a much more assertive China."

Once the shock reaches the surface, energy is released in enormous amounts and the supernova becomes visible.

A smooth stock market on the surface is masking nerves and turbulence.

Then there are sea drones: uncrewed vessels that can travel either on or below the surface, as used with devastating effect by Ukraine against Russia's Black Sea fleet.