Dunne is an Irish surname, derived from the Irish O ó duinn AND O, ó doinn meaning dark.. Or brown The name Dunne in ireland is derived FROM The o ó DUINN And The O ó doinn gaelic septs Who Were based In County. Laois and county wicklow these septs in turn Are'Descendants of the. o regan noble familyoth Gaelic names are derived from the Gaelic word donn, which means brown. O ó doinn is the genitive case of. Donn first found in County, meath where they held a family seat from very ancient. Times: Variations, Dunn, Dunne, Dun'O, Dunne'O, Doyne, Doine, Doin'O. dunn