Meaning of in hoc signo vinces*

in hoc sig•no vin•ces

Pronunciation: (in hōk' sig'nō wing'kās Eng. in hok' sig'nō vin'sēz), [key]
— Latin. Latin.
  1. in this sign shalt thou conquer: motto used by Constantine the Great, from his vision, before battle, of a cross bearing these words.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.