cosmic microwave background

Etymology
It was originally called the primeval fireball.

Noun

 * 1)  Faint thermal radiation that pervades all space and is thought to be the remnants of the big bang, produced during the epoch of recombination.

Translations

 * Finnish: kosminen taustasäteily, avaruuden taustasäteily
 * French:
 * Polish: mikrofalowe promieniowanie tła