Green’s Dictionary of Slang

1. grandfather.

1935		S. Lewis It Can’t Happen Here 114: ‘Swell bunch o’ tin soldiers! Nine o’ yuh to one grandpappy! Just about even—’.
1941		N. Davis ‘Don’t Give Your Right Name’ in Goulart (1967) 23: They got a whole bunch of corporate accounts they inherited from their grandpappies.
1948		(con. 1944) N. Mailer Naked and Dead 514: His granpappy used to have an ole nigger woman bleed him.

2. see grand-daddy n.