From pop + -sy (hypocoristic suffix), compare pops.
Meanings
(informal) Grandfather.
(informal) Father.
Dear Popsy,
I need your help. Mother writes that if I don't return the leg immediately she will come to the school and take it by force. You must stop her, Popsy. 2013, Eric Bishop-Potter, Dear Popsy: Collected postcards of a private schoolboy to his father, Troubador Publishing, page 51:
Pilots are often interested in nothing but popsies, kites, and beer. 1943, H. E. Bates, There's Something in the Air:
Your wife will be pleased to be taken to a lovely hotel and out on the river for breakfast. Your popsy won’t. She’ll take it as her due. 2000 May 14, Michael Bywater, “One man in a boat – but who should he take?”, in The Independent on Sunday, number 536, London, →ISSN, →OCLC, Travel section, page 1, column 4: