The story
- Irish · derived fromÓ Gealagáin“descendant of Gealagán”
- English todayGalligan
Reduced Anglicized form of Irish Ó Gealagáin (“descendant of Gealagán”), a personal name which derives from a double diminutive of geal (“bright, white”).
Etymology from Wiktionary, CC BY-SA 4.0.