What is "geoghegan"

Geoghegan is a surname of Gaelic Irish origin.

Often spelt without the prefix "Mac", the name has many variants, including Gehegan, Geoghan, Geohegan, Gahagan, Gagan, and Gagon which approximate the most common pronunciations of the name. It is usually pronounced gay-gan, ge-heg-an or go-hee-gan. In Irish it is Mac (or Mag) Eochagáin, from Eochaidh. The initial "G" of Geoghegan comes from the prefix Mag, a variant of Mac and the anglicised form Mageoghegan was formerly much used.