Andrew,
Is this something from Matthew Poole's writing? Can you provide the full sentence that this came out of?
Of the responses I've gotten so far, one person thinks it could be a spelling mistake and suggested the following ....
mactus (1) -a, -um: glorified, honored; used only in voc. m.: macte, well done!, bravo! good luck!
mactus (2) -a, -um: smitten
Another said
"It's not classical Latin, but googling produces some hits from old
dictionaries of Coptic and Aramaic that you might like to look at."
So some additional context might be helpful.