Atavus
Black's Law Dictionary · Henry Campbell Black, M.A. · 1910
Black's Law Dictionary
The great-grandfather's or great-grandmother's grandfather; a fourth grandfather. The ascending line of lineal ancestry runs thus: Pater, Avus, Proavus, Abavus, Atavus, Tritavus. The seventh generation in the ascending scale will be Tritavl-pater, and the next above it Proavi-atavus.