C 外祖父，外公；祖父，爷爷　 the father of your mother or father

1. grandfather的基本意思是“（外）祖父”，指父亲或母亲的父亲。
2.与grandfather相对应的阴性名词是grandmother.

　great ～　曾祖父
　～ clock　旧式大时钟

　His grandfather is a veteran of the Second World War.　他的祖父是一位参加过第二次世界大战的老战士。
　Although he is over 70, my grandfather is very strong.　尽管我爷爷70多岁了，但他仍然很健壮。
　His grandfather became ill from anxiety.　他的爷爷由于焦虑而病倒了。