(n.) A father's or mother's father; an ancestor in the next degree above the father or mother in lineal ascent.

Father Time Methuselah Nestor Old Paar centenarian dotard elder gaffer geezer golden-ager grampa gramps grandpa grandsire graybeard great-grandfather nonagenarian octogenarian old chap old codger old dog old duffer old geezer old gent old gentleman old man old party old-timer older oldster pantaloon patriarch presbyter senior citizen septuagenarian sexagenarian the quiet-voiced elders venerable sir veteran