2. A certificate that a ship or vessel has been cleared at
the customhouse; permission to sail.
Every ship was subject to seizure for want of
stamped clearances. --Durke
3. Clear or net profit. --Trollope.
4. (Mach.) 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.
{Clearance space} (Steam engine), the space inclosed in one
end of the cylinder, between the valve or valves and the
piston, at the beginning of a stroke; waste room. It
includes the space caused by the piston's clearance and
the space in ports, passageways, etc. Its volume is often
expressed as a certain proportion of the volume swept by
the piston in a single stroke.