In the new Nicene Creed at church the other night, I was thinking about the use of the term consubstantial when we now say “consubstantial with the Father.” I understand that in the Latin original, the term there is consubstantialem. Here it seems the prefix “con” means “same.” Yet in etymology dictionaries, they say it means “together” or “with.” I suppose “together” could suggest a sameness there. But I know when the early uses of the term consubstantial came out to describe the Lutheran position, (which teaches Christ “in, with, and under” the bread) does not suggest sameness, but rather “with.” So what is the proper etymology? Or can the prefix mean both “same” and “with” depending on context?
It is, perhaps, important to remember that the actual Niceno-Constantinopolitan Creed is in Greek, not Latin.
Consubstantialis isn’t even a real Latin word; it was invented in an attempt to translate the Greek because Latin lacked any word good enough to carry the import of what the Creed was trying to say. If there is any question about what the Latin means, then, the appropriate place to look is the Greek original.
And the original Greek word was
homoousion. You can read the Catholic Encyclopedia article about it
here. The prefix
homo- definitely means “same,” but as the article explains there is ambiguity about whether it means “the exact same” or “the same type.” You’ll note that Tertullian translated it into Latin with the expression
unius substantiae, which literally means “of one substance,” which as Chatter points out is exactly how the BCP renders it.
As to the actual Latin prefix
con-, it is a form of the word “cum.” “Cum” by itself has a ton of different meanings, mostly “with” but also “when,” “since,” “and,” “under the condition that,” and so on.
Lewis & Short explains that when it is made a prefix
It designates,
1. A being or bringing together of several objects: coëo, colloquor, convivor, etc.: colligo, compono, condo, etc.—
2. The completeness, perfecting of any act, and thus gives intensity to the signif. of the simple word, as in commaculo, commendo, concito, etc., comminuo, concerpo, concido, convello, etc.