optatio

[641] The outward form of _co-optatio_ was still preserved, like our "election" of a bishop by a chapter.

The Religious Experience of the Roman People From the Earliest Times to the Age of Augustus W. Warde Fowler 1884

_ -- Sulla repealed the Lex Domitia, which gave to the Comitia Tributa the right of electing the members of the great ecclesiastical corporations, and restored to the latter the right of co-optatio, or self-election.

A Smaller History of Rome William Smith 1853