Q: HI there, Fr. Paul, I hope that you are well today. I was asked an interesting question this morning, and have not ever heard of this before, and thought you might have some insight.
The question was first asked of my new colleague. We are fairly sure that it was a hypothetical question, not a question from someone’s actual experience! 
Would the use of the term “Holy Ghost” rather than “Holy Spirit” invalidate a baptism?
Please let me know what you think and thanks in advance for your time!
Peace in Christ,
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A: This is a canonical question, not a liturgical one, so I defer to your local canon lawyers for a more decisive answer. But from my point of view, there has been no indication from the Vatican about this particular matter, whereas there have been plenty of indications from the Vatican that they want the approved formula, only the approved formula, and nothing but the approved formula.
Since we have no instructions otherwise, it’d probably be a valid baptism, though illicit, but pleasepleasepleasepleaseplease do not let people baptize that way. It’s inviting problems.
And check with a canonist for a more authoritative reply.