CMB uncommon noun 1. (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 Synonymscosmic background radiationCBRcosmic microwave background radiationCMBRcosmic microwave background Related words Broader terms cosmic radiation WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
