There is no such word as “epithany”—nor is it “epifany,” nor “epuphany,” nor any of several other imaginative spellings I’ve seen in manuscripts (and on blogs and Facebook) lately.
Epiphany—as it’s most commonly used in stories and among writers—is when a character experiences a sudden moment of perception, insight or revelation of deeper meaning or direction.
An author might have an epiphany about a character or plot line.
A character might have an epiphany about the meaning of his/her life.
In the case of a character, it should be rare. Limit yourself to one per book.
Wow, I'll be the first to admit while I have them, and talk about them, I don't spell it correctly. Thanks for the heads up. They must not be in my MS because my spellcheck would have caught that one, right?
As a former Anglican I know the background to the word. When I was growing up, Epiphany was a festival celebrated in January, commonly known as "The Twelfth Day of Christmas" and traditionally the time the wise men visited the infant Jesus. I think it came to mean a special revelation because that was when Jesus was revealed to the gentiles (i.e., the magi).