In Star Trek Discovery Season 2 Episode 11 Perpetual Infinity, the mirror Philippa Georgiou says:
You have obviously confused me with my sentimental prime universe counterpart. I'm Terran.
As far as I know, this is the first and only time the term 'prime universe' is used in-universe. Are there other instances where this naming is used in-universe? And, wouldn't the mirror Georgiou think that her universe is the prime one?