gran'pa

Noun

grandpa (plural grandpas)

1. (informal) grandfather.
2. (colloquial) Any elderly man, regardless of if he has, or whether one knows he has, grandchildren.
   • Pointing to the ‘No Smoking’ sign on the wall, he said we must stop smoking. ‘All right, grandpa!’ someone said.1933, Frank Clune, Try Anything Once, Sydney: Angus and Robertson, page 137

See all 3 meanings of grandpa