1. (cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature
   - big bang theory

Type of: scientific theory

• extragalactic nebula
• extrajudicial
• extralegal
• extralinguistic
• extramarital
• extramarital sex
• extramundane
• extramural
• extraneous
• extraneousness
• extranet
• extraordinaire
• extraordinarily
• extraordinariness
• extraordinary
• extrapolate
• extrapolation
• extrasensory
• extrasensory perception
• extrasolar
• extrasystole
• extrasystolic
• extraterrestrial
• extraterrestrial being
• extraterrestrial object