About the McMillan surname
The surname McMillan is associated with a patronymic formation. The Mac-/Mc- formation is traditionally patronymic and means “son of” in Gaelic languages. The name therefore belongs to a tradition in which an ancestor's given name gradually became a hereditary surname. The prefix in McMillan belongs to a family of Gaelic forms traditionally used in patronymic surnames and is generally associated with descent.
Pronunciation:
Èm-sé-mi-lan/ɛmsemilɑ̃/