Clare Genealogy: Short Study of a Transplanted Family in the Seventeenth Century: Appendix A: Origin of MacLysaght Name

Appendix A: Origin of MacLysaght Name

While the Dalcassian origin of the family may be taken out as not open to doubt, there is less certainty as to the origin of the name itself. Disregarding such far-fetched guesses as lae seacht (which has been solemnly suggested as the derivation) there is still more than one possible derivation, and I am not prepared to take as finally proved the generally accepted origin of the word, that given by Father Wolfe in his Sloinnte Gaedheal a’s Gall, viz., Mac Giollaiasachta, though in common with all other MacLysaghts who make any use of the Irish language that is the form in which I sign my name. O’Hart gives Mac Giolla Iosa i.e., the son of Giolla Iosa O’Brien, a form which, aesthetically at least, I find more attractive if less probable. The fact, however, that the name first appears in English as Macgillysachty is fairly conclusive evidence that it was Mac Giollaiasachta in Irish.