In hoc signo vinces

"In hoc signo vinces" (Classical Latin: [in ho̞ːk s̠íŋno̞ː wíŋke̞ːs̠], Ecclesiastical Latin: [in ok ˈsiɲo ˈvint͡ʃes]) is a Latin phrase conventionally translated into English as "In this sign thou shalt conquer", often also being translated as "By this sign, conquer".

The Latin phrase itself renders, rather loosely, the Greek phrase "ἐν τούτῳ νίκα", transliterated as "en toútōi níka" (Ancient Greek: [en túːtɔːi̯ níːkaː], Modern Greek: [en ˈduto ˈnika]), literally meaning "in this, conquer".