The name Keegan is an Irish baby name. In Irish the meaning of the name Keegan is: A thinker; fiery. Form of Hugh. The name Keegan is an American baby name. In American the meaning of the name Keegan is: A thinker; fiery. Form of Hugh. The name Keegan is a Celtic baby name. In Celtic the meaning of the name Keegan is: Son of Egan. The name Keegan is a Gaelic baby name. In Gaelic the meaning of the name Keegan is: Small and fiery.