Family History and Genealogy Resources by Surname
Kirwan Surname Origin
The name was O'Quirivane until the time of Queen Elizabeth, when they, with many Irish houses, were compelled to drop the 'O,' and Quirivane was corrupted into Kirwan.
Source: An Etymological Dictionary of Family and Christian Names With an Essay on their Derivation and Import; Arthur, William, M.A.; New York, NY: Sheldon, Blake, Bleeker & CO., 1857.
Kirwan Surname Meaning and Family Facts
There is more to Kirwan family history than the origin of your surname:
A Kirwan Family History Thought:
'If man cares not for his roots, then how can he care for his branches?' --Doyle M Davis