'''''Homoousios''''' is a Greek word meaning "same substance" or "same essence." It is used in the [[Nicene Creed]] to say that Jesus Christ is of one essence with the Father. Although it does not appear in the Bible, the fathers of the [[First Ecumenical Council]] ultimately decided that this was the best language to use concerning the [[Holy Trinity]].
The competing term at that council was ''homoiousios'' meaning "similar essence"; it was favored by the [[Arianism|Arians]]. Because of how close these two words are in the Greek, it has been said that there was only "one iota" of difference between them.