Mac An Ridire
Mac an RIDIRE—VII—M'Eridery, M'Iruddery, M'Ruddery, MacRuddery, MacKnight, Knight, [Fitzsimons, FitzSimons]; 'son of the knight' (Irish 'ridire'); the Irish surname assumed by the FitzSimons of Co. Westmeath, and perhaps also by offshoots of knightly houses in other parts of Ireland.
Alphabetical Index to Irish Surnames