Monday, Munday, Mundy
Monday, Munday, Mundy—These three names in S. West Ulster and adjoining parts of North Connacht, particularly in the County of Cavan, Lisnaskea in Co. Fermanagh, and Clones, Co. Monaghan, are the anglicised forms of McAloon, M'Clune, and M'Lune; in Gaelic Mac Giolla-Eóin.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees