If there is no doubt about it, it's unequivocal. An unequivocal response to a marriage proposal? "Yes. Yes! A thousand times yes!"
Equivocal is from a Latin word meaning of equal voice, so unequivocal means of unequal voice — unmistakable, unambiguous, without question. There might be unequivocal evidence tying a suspect to a crime, or unequivocal support for a popular leader. If you explain something in unequivocal terms, then your words should be clear to everyone.