Also includes the surname derivative of DONAHUE

Scottish: from the Older Scots personal name Dunecan itself from the traditional Irish royal name Donnchad(h) derived from donn ‘brown-haired’ + cath ‘battle’. Judging by the Scots form the Scottish Gaelic intermediary seems to have been understood as containing ceann ‘head’ as if the whole name meant ‘brown head’; compare sense In Ireland the name was Anglicized as Donagh or Donaghue. Compare Donahue . Irish: used as an Anglicized equivalent of Gaelic Ó Duinnchinn ‘descendant of Donncheann’ a byname composed of the elements donn ‘brown-haired man’ or ‘chieftain’ + ceann ‘head’.

Source: Dictionary of American Family Names 2nd edition, 2022