Tanist \Tan"ist\, n. [Ir. tanaiste, tanaise, second, the second
person in rank, the presumptive or apparent heir to a
prince.]
In Ireland, a lord or proprietor of a tract of land or of a
castle, elected by a family, under the system of tanistry.
[1913 Webster]
This family [the O'Hanlons] were tanists of a large
territory within the present county of Armagh. --M. A.
Lower.
[1913 Webster]