General Definition: 1. The action of holding something in your hand at eye level and moving it up and down at either end, or any thing or any action directly or indirectly associated with this, especially a spirit level. As a Noun: 1. A device for testing a surface to see if it is level. It consists of a piece of wood or metal containing a tube of liquid with a bubble of air in it. When it is level the bubble is in the centre of the tube. English = spirit level.