Recorded in several modern forms including Tomelty, Tumelty, Tumbelty, Tumblety, Tumilty and Tumulty, this is an ancient Irish surname. It originates from the pre 10th century Gaelic O' Tomaltaigh or Mac Tomaltaigh, and like most early Irish surnames was probably a nickname for the first chief of the clan. It derives from the word "tomaltach" meaning large or bulky! This was the usual means by which Gaelic surnames developed, whereas in other parts of the British Isles the developments were more usually from locations, occupations, and simple patronymics. Irish surnames are patronymics but they commence as nicknames, some of which were, if not actually obscene, certainly very personal, although nobody seems to have minded! The prefix either O' meaning descendant of, or Mac, the son of, seem to have disappeared from this name completely by the 16th century, and are no longer believed to be in use anywhere. In fact it is said that in Ireland the clan is greatly reduced, being almost extinct, but with some survivors being found in the barony of Moycarn in County Roscommon, and others at the junction of counties Monaghan, Louth, and South Down. The first nameholder is believed to have been Cormac Tomaltach, given as being chief of Moylurg from 1169 to 1206, whilst one Teag O' Tumulty was the canon of Elphin in about 1296.