The Buddha would be the right way to say it. "The Buddha" is a title used in the same way as other titles such as "The President" or "The Pope" when referring to the individual by title and not by name.
Gautama Buddha created the religion of Buddhism therefore I think he knows what a Buddha does, although it had changed through out the ages, the important stuff has stayed the same
"Buddha" means "the Fully Enlightened One"Buddhahood is attained through the realisation of the intrinsic / true nature of all things in the universe, including existence / mind & body / life;...
Buddha basically means one who has attained enlightenment. More specifically they did it without a teacher to show them the Dharma (teachings of Buddhism), and then taught the Dharma to others. It is...