The noun farewell refers to the act of departing. After 25 years with his company, your dad's farewell was a sad day for everyone except for the person taking his place — she was actually pretty happy about her promotion.
A farewell is also an expression of good wishes at a parting. Some families are so large and emotional that the farewells after a family gathering seem to take hours. Farewell was originally an interjection, like "goodbye," said at partings. It is a combined form of fare and well. Fare comes from the Old English word faran, which means "to journey."
