| Noun | 1. | 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 CMB, CMBR, cosmic background radiation, cosmic microwave background, cosmic microwave background radiation cosmogeny, cosmogony, cosmology - the branch of astrophysics that studies the origin and evolution and structure of the universe cosmic radiation - radiation coming from outside the solar system |