Gainemain: a river in Conalle Murthemni
Garech: the name of the hill where the final battle of the Táin was fought, some distance south-east of Athlone and near Mullingar, in Westmeath
Gegg: a woman's name
Genonn Gruadsolus: a druid and poet of Ulster; son of Cathba
Glaiss Colptha: the river Boyne
Glaiss Gatlaig: a river in Ulster
Glenamain: a river in Conalle Murthemni
Glenn Fochain: probably a valley east of Bellurgan Station
Glenn Gatt: a valley in Ulster
Glennamain: in Murthemne