| 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 |