fa·mil·ial \fəˈmilyəl, -lēəl\adjective Etymology: French, from Latin familia family + French -al 1.: of, relating to, or having the characteristics of a family < children of the same familial background — E.L.Volpe > 2.: having a tendency to occur in different members of a family to a degree greater than chance would allow < a familial disease > — compare congenital, hereditary