What is "lafferty"

Lafferty is a sept of Irish Gaels in County Donegal and County Tyrone, belonging to the Cenél nEógain of the Northern Uí Néill. They are a branch of the O'Neill family and are named after one of the earlier Kings of Ailech called Flaithbertach mac Muirchertaig meic Néil. They are not to be confused with the O'Flaherty family of Connacht. Other anglicised versions of the name are O'Laverty, O'Lafferty and Laverty.