How to say 'before previous' in one word?

I'm struggling to say 'before previous' in one word. Like "I visited my parents pre-previous month". Is there a suitable word?

Solution 1:

As in comments, "two months ago" or "the month before last" are common ways to phrase this. As also noted on comments, some folks will drop "the" from "the month before last." That's a pretty informal mode of speech, but bear in mind that there's another "month" implied in the phrase already "the month before last [month]."

Solution 2:

If you really need a single word, just give the name of the month.

Solution 3:

A late answer but you can say "penultimate".