from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
ENTIA PARS. The part of the eldest. Co. Litt. 166; Bac. Ab. Coparceners, C.
2. When partition is voluntarily made among coparceners in England, the
eldest has the first choice, or primer election, (q.v.) and the part which
she takes is called enitia pars. This right is purely personal, and
descends; it is also said that even her assignee shall enjoy it; but this
has also been doubted. The word enitia is said to be derived from the old
French, eisne the eldest. Bac. Ab. Coparceners, C; Keilw. 1 a, 49 a; 2 And.
21; Cro. Eliz. 18.