clearance

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act or process of clearing.
2. n. A space cleared; a clearing.
3. n. The amount of space or distance by which a moving object clears something.
4. n. The height or width of a passage: an underpass with a 13-foot clearance.
5. n. An intervening space or distance allowing free play, as between machine parts.
6. n. Permission for an aircraft, ship, or other vehicle to proceed, as after an inspection of equipment or cargo or during certain traffic conditions.
7. n. Official certification of blamelessness, trustworthiness, or suitability.
8. n. A sale, generally at reduced prices, to dispose of old merchandise.
9. n. The passage of checks and other bills of exchange through a clearing-house.
10. n. Physiology The removal by the kidneys of a substance from blood plasma.
11. n. Physiology Renal clearance.

Century Dictionary and Cyclopedia

1. n. The act of clearing; riddance; removal of encumbrance or obstruction: as, the clearance of land from trees; the clearance of an estate from unprofitable tenantry.
2. n. Clear or net profit.
3. n. A certificate that a vessel has complied with the law and is authorized to leave port. It contains the name of the master, of the vessel, and of the port to which it is going, a description of the cargo, and other particulars. The manner in which a clearance shall be made is prescribed by law.
4. n. In steam-engines, the distance between the piston and the cylinder-cover, when the former is at the end of its stroke; similarly, free play for the parts of any other machine; clearing.
5. n. A piece of land which has been cleared for cultivation or for building; a clearing.
6. n. In railroading: A difference between the track-gage and the gage of the exterior surface of the wheel-flanges, designed to allow a certain amount of play between the flanges and the rails.
7. n. At a crossing or frog, the clear space left between cross-rails and the frog and guard-rail for the free passage of the flanges of the wheels.
8. n. The clear space between the sides and top of a tunnel or bridge and the outside dimensions of the largest car passing through it.
9. n. In steam-engines, the volume or entire space below the valve-face which is filled with steam at the beginning of a stroke, including the space between piston and cylinder-head and the volume of the steam-ducts to the valve-seat.
10. n. The settlement or payment of a debt; the passing of checks and drafts through the clearing-house for their settlement.

Wiktionary

1. n. The act of clearing or something (such as a space) cleared
2. n. The distance between two moving objects, especially between parts of a machine
3. n. The height or width of a tunnel, bridge or other passage, or the distance between a vehicle and the walls or roof of such passage; a gap, headroom.
4. n. A permission for a vehicle to proceed, or for a person to travel.
5. n. A permission to have access to sensitive or secret documents or other information
6. n. A sale of merchandise at a reduced price.
7. n. banking, finance The settlement of transactions involving securities or means of payment such as checks by means of a clearing house.
8. n. medicine The removal of harmful substances from the blood; renal clearance.
9. n. sports, billiards, snooker, pool The act of potting all the remaining balls on a table at one visit.
10. n. soccer The act of kicking a ball away from the goal one is defending.

GNU Webster's 1913

1. n. The act of clearing.
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. (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.

WordNet 3.0

1. n. the distance by which one thing clears another; the space between them
2. n. permission to proceed
3. n. vertical space available to allow easy passage under something