Sentence:  <WSD>Grandfather</WSD> was friendly, formal, and strict with the children in his large family, and quite displeased with the lively goings-on of the grandchildren. ... He only joked with me once, when I was four, and never again. Our festive Sunday dinner was crowned by a pudding. Perhaps I looked too greedy—<WSD>Grandfather</WSD> threatened to throw the pudding out of the window. It is reported that I answered, "Then I'll jump out of the window and gobble it up all by myself." 
Meaning of the word marked with <WSD> tags:  A father of someone's parent. (from 15th c.)