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?

Answer

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]."