"Unequivocably" vs. "unequivocally"

Solution 1:

The correct word is unequivocally. Unequivocably is wrong.

According to Merriam-Webster, unequivocably is a non-standard word for unequivocally. Its first known use was in 1917.

The word (unequivocally) was perhaps altered by drawing an analogy between unequivocal and, say, understand. Understand changes to understandably, so they changed unequivocal to unequivocably. Though, as I said, it's wrong.