Planing has several meanings:

• With boats, planing or hydroplaning is a method by which a hull skims over the surface of the water, rather than plowing through it.
• With rubber wheeled vehicles, aquaplaning, planing or hydroplaning is a cause of loss of steering control when a layer of water prevents direct contact between the tires and the road surface.
• In woodworking, planing is the activity of using a wood plane to smooth a flat surface of a piece of wood.
• In music theory, planing is where chords move in parallel motion, thereby eliminating any feeling of harmonic progression.

The above terms can vary in meaning, particularly comparing usage of the first two terms in the US and in Europe.