Meaning of protogalaxy

pro•to•gal•ax•y

Pronunciation: (prō"tō-gal'uk-sē, prō'tō-gal"-), [key]
— pl. -ax•ies.
  1. the large concentration of gas and dust from which a galaxy is formed.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.