The Irish word for grandfather is seanathair, literally meaning "old father." Children would not be likely to address a grandfather by this term. They would use instead daideó or móraí.
Irish names for grandparents have not been widely adopted by those of other ethnicities, as some other grandparent names have been. This is probably due to the complexity of the spelling and pronunciation.
Learn about Irish names for grandmother.
See also a comprehensive list of grandfather names.
Pronunciation: Learn how to pronounce seanathair.
Also Known As: Other terms for grandfather include athair mór (great father) or athair críonna (father of the heart).