Noah Webster's New International Dictionary of the English Language

1. (n.) The act of clearing; as, to make a thorough clearance.

2. (n.) A certificate that a ship or vessel has been cleared at the customhouse; permission to sail.

3. (n.) Clear or net profit.

4. (n.) The distance by which one object clears another, as the distance between the piston and cylinder head at the end of a stroke in a steam engine, or the least distance between the point of a cogwheel tooth and the bottom of a space between teeth of a wheel with which it engages.