Original: A vocation, from the Latin vocare (verb, to call), is a term for an occupation to which a person is specially drawn or for which they are suited, trained or qualified.
Simplified: The word "vocation" comes from the Latin vocare, meaning "to call"; Richard A. Muller, Dictionary of Latin and Greek Theological Terms: Drawn Principally from Protestant Scholastic Theology (Grand Rapids, Michigan: Baker Book House Company, 1985), s.v. "vocatio."