cosmic microwave background vs CBR

cosmic microwave background and CBR both are nouns.

Word	Noun	Adjective	Verb	Adverb
cosmic microwave background	Yes	No	No	No
CBR	Yes	No	No	No

As nouns, cosmic microwave background and CBR are synonyms defined as:

cosmic microwave background and CBR: (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

Other synonyms of cosmic microwave background include CMB, CMBR, cosmic background radiation, cosmic microwave background radiation.

cosmic microwave background (noun)	CBR (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	(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