standard candle

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A candela.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun astronomy Any astronomical object of known absolute magnitude. Its distance can then be calculated from its apparent magnitude.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the basic unit of luminous intensity adopted under the Systeme International d'Unites; equal to 1/60 of the luminous intensity per square centimeter of a black body radiating at the temperature of 2,046 degrees Kelvin