Board Thread:Questions and Answers/@comment-30128802-20170721015222/@comment-30128802-20170721201741

Ah, good find. So that term did exist in a semi-official source. I don't think "Prima" is a typo, since it would be a typical example of pseudo-Latin. It's certainly not the only example of awkward expressions in a non-English languages.

An interesting thing about that quote is that it says "a" Prima Illuminatus, rather than "the" Prima Illuminatus. It's a bit ambiguous whether there could be more than one at the same time. But Black Light seems to have canonized it as a title that Lucius uses for himself.