Phrase guide

cosmic microwave background

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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1

noun

Meaning 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.

Definition source: English Wiktionary via Wiktextract

Usage: uncountable

Topics: astronomy, natural-sciences

Examples

  • Holonyms: cosmic background, cosmic background radiation < electromagnetic radiation < radiation

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

(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

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: cosmic background radiation, CBR, cosmic microwave background radiation, CMBR, CMB

Antonyms: none provided

Broader terms: cosmic radiation

History

Etymology

It was originally called the primeval fireball.

Across languages

Translations

5 source translations are retained for this English entry.

  • Finnish: kosminen taustasäteily — Translations
  • Finnish: avaruuden taustasäteily — Translations
  • French: fond diffus cosmologique — Translations
  • Georgian: კოსმოსური მიკროტალღური ფონი (ḳosmosuri miḳroṭalɣuri poni) — Translations
  • Polish: mikrofalowe promieniowanie tła — Translations