cosmic background radiation

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

• noun astronomy The faint, uniform flux of microwave radiation that permeates all space and is the redshifted residual effect of the Big Bang

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

• noun (cosmology) the cooled remnant of the hot big bang that fills the entire universe and can be observed today with an average temperature of about 2.725 kelvin