Here's why:
* Unequivocal means clear, definite, and leaving no room for doubt.
* Ambiguous means open to more than one interpretation, unclear, or uncertain.
Here are some other words that could be considered opposites of unequivocal:
* Doubtful
* Indefinite
* Uncertain
* Vague
* Open to interpretation
* Contestable
The best word to use as an opposite of unequivocal depends on the specific context.