Mac Caisín
Mac CAISÍN—IV—M'Cashine, M'Kasshine, M'Cassin, MacCashin, Casheen, Cashin, Cashen, Cashion, Cassin, Keshin, &c.; 'son of Caisín' (diminutive of cas, bent, curly); a well-known family in Leinster and parts of Munster, where they were formerly hereditary medical practitioners; also an Antrim family.
Alphabetical Index to Irish Surnames