いつものDave Armstrongのサイトから拾ってきますた。 http://ic.net/~erasmus/RAZ19.HTM
>8) "Co" in Latin does not mean "equal"; it merely means "with" or "alongside." We see this even in English. If you have a "co-pay" with regard to health insurance, that doesn't mean that you always pay equally with your insurance provider (I sure hope not!). "Co-Pilot" sometimes means "equal" but usually not. Etc. But because the term Co-Redemptrix is so misunderstood, it has fallen out of use in the last 50 years or so. But nevertheless, Pope John Paul II has used it at least five times, as Dr. Miravelle notes.