Tanistry, a method of tenure which prevailed among the Gaelic Celts; according to this custom succession, whether in office or land, was determined by the family as a whole, who on the death of one holder elected another from its number; the practice was designed probably to prevent family estates falling into the hands of an incompetent or worthless heir.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Tanist Stone * Tanjore