Ma'anar ƙamus na kalmar CMBR shine "Cosmic Microwave Background Radiation". Yana nufin radiation electromagnetic da aka yi imani da cewa shi ne ragowar zafi daga Big Bang, wanda ya faru kimanin shekaru biliyan 13.8 da suka wuce. Wannan radiation iri ɗaya ce ta kowane bangare kuma tana da zafin jiki kusan 2.7 Kelvin (-270.45 digiri Celsius ko -454.81 digiri Fahrenheit). Ana ɗaukarsa a matsayin tushen mahimman bayanai game da sararin samaniya na farko kuma masana ilimin taurari da masana sararin samaniya suna yin nazari sosai.