Swift
Swift—This name is the anglicised form of Fodaghan (O'Fuadachain) in the Counties of Cavan, Monaghan and those adjoining; Foody (O'Fuada) in the Northern parts of Connacht, except in the districts about Ballyhaunis, Co. Mayo, where the name Speed is the anglicised form.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees