Mac Geargáin
Mac GEARGÁIN—IV—M'Geregan, M'Gergaine, M'Gargan, MacGerrigan, MacGarrigan, Garrigan, Gargan; 'son of Geargán' (diminutive of gearg, fierce); an old surname in Meath and Cavan; also Ó Geargáin, which see.
Alphabetical Index to Irish Surnames