TANISTRY
Etymology
Noun
tanistry (usually uncountable, plural tanistries)
(historical) A form of tenure, in ancient Scotland and Ireland, whereby succession was passed to an elected member of the same extended family.
Source: Wiktionary
Tan"ist*ry, n. Etym: [See Tanist.]
Definition: In Ireland, a tenure of family lands by which the proprietor
had only a life estate, to which he was admitted by election.
Note: The primitive intention seems to have been that the inheritance
should descend to the oldest or most worthy of the blood and name of
the deceased. This was, in reality, giving it to the strongest; and
the practice often occasioned bloody feuds in families, for which
reason it was abolished under James I.
Source: Webster’s Unabridged Dictionary 1913 Edition