grandpa; gramps
Affectionate, honorific term for one's own grandfather or an elderly man, used mainly by young children or in a childish, familiar register. More endearing than おじいちゃん.
Good morning, Grandpa!
Grandpa took me to the park.
おじいさん is a standard polite term for an elderly man or one's own grandfather; おじいちゃま is more intimate and childish.
Kanji form using 爺; rarely used in practice.
Kanji form using 祖父; rarely used in practice.
Derived from おじいさん (grandfather) with the honorific suffix ちゃま, a childish or affectionate variant of さま (honorific).