the act of clearing; as, to make a thorough clearance.-a certificate that a ship or vessel has been cleared at the customhouse; permission to sail.-clear or net profit.-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.