释义 |
clear·ance \ˈklirən(t)s\ noun (-s) 1. : the act of making clear of whatever may obstruct, occupy, encumber, or hinder: as a. : the removal of buildings from an area (as a city slum) in order to permit new construction b. (1) : the act or an instance of clearing a ship at the customhouse (2) or clearance papers : the papers showing that a ship has cleared c. : the offsetting of checks and other claims among banks through a clearinghouse, the Federal Reserve banks, or other agencies d. : approval or certification as clear of objection, prohibition, suspicion, or guilt < security clearance of those with access to secret atomic information — J.G.Palfrey > < given clearance by the FBI > : permission to proceed without objection, check, or reservation < you have to have the general's personal clearance — J.G.Cozzens > e. : the sale usually at reduced prices of stock (as excess inventory) which it is desired to move from the store < a January clearance of men's suits > f. : authorization for an airplane to proceed under specified traffic conditions 2. : the distance by which one object clears another or the clear space between them < a car with a road clearance of 7 1/8 inches > < a bridge with a 100 foot clearance above water > as a. (1) : the distance between the piston and the cylinder head at the end of a stroke in an engine (2) : the total volume (as of steam) remaining in the cylinder and ports at the end of the exhaust or compression stroke; also : the line or area on an indicator diagram noting this distance or volume b. : the space between adjacent structural members or their component parts to allow for inaccuracies in cutting and to permit them to be placed in a structure c. : the distance by which the top of a gear tooth clears the bottom of the space between two teeth on the mating gear d. : the margin of space between the structures along a railroad track (as poles, buildings, or tunnel walls) and the periphery of the largest locomotive or car that will pass over that track e. or clearance angle : the angle between the face of a cutting tool and the work f. : the interval stipulated in the lease of a motion picture that must elapse after the film's exhibition in a first-run theater before it can be leased to other theaters within a specified surrounding area g. : a quantitative measure of renal efficiency in the transfer of any solute from the blood to the urine, being determined as the volume of blood that would be freed of a specified constituent by removal of a quantity equal to the measured renal excretion of that constituent during one minute — called also renal clearance 3. : a space or area that has been cleared of that which formerly occupied it (as trees or brush) < a clearance in the forest > < clearances, the Highland equivalent of enclosures, in which the … peasants were treated … as mere squatters — Russell Kirk > 4. : a permission-to-work order to a line crew after a power line has been de-energized for the crew's safety 5. : a part of a foundry mold or core beveled off to prevent contact of friable surfaces when closing the mold Synonyms: see room |