Masterson, Masterman, Masterton
Masterson, Masterman, Masterton—These three names are the anglicised forms of M'Kernan in S.W. Ulster, in South Fermanagh and in Co. Cavan. It is also rendered McMasters. In the second case it is in N.E. Ulster and Scotland the anglicised form of Mac Master (Mac Mháighistir), a sept of the Mac Farlanes in Dumbarton Co., Scotland.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees