Was Buddha A Monk?

Before his enlightenment the Buddha, then Prince Siddhartha, ordained himself as a monk, so yes.

Buddha was born to a wealthy family of the highest caste in India. As a young man, he saw that everything was subject to decay and death and sorrow, including himself, so he renounced his status and riches to wander off and seek nirvana. 

There's a beautiful story about 'what Buddha was'...it's said that a disciple found him meditating one day and asked him, "Lord Buddha, are you a God?" and the Buddha replied, "no." He asked, "Lord Buddha, are you a saint?" And Buddha replied "no." He asked "lord Buddha, are you a prince?" And Buddha replied again, "no." So the man asked "well, if you are not a God, a saint or a prince, then what are you?" And the Buddha replied, "I am awake."