Sionnach
SIONNACH—X—Shinnagh, Shinnock, &c., and by translation Fox, Foxe; Irish 'Sionnach,' i.e., the fox; an epithet or nickname which supplanted the real surname, especially in the case of the family of Ó Catharnaigh (which see), anciently chiefs of Teffia.
Alphabetical Index to Irish Surnames