Webster's Revised Unabridged Dictionary · 1913

co-optation

co-optation , noun

[Latin cooptatio.]

The act of choosing; selection; choice. [Obsolete]
The first election and cooptation of a friend. — Howell
2.
the selection of a new member (usually by a vote of the existing membership). See co-opt{2}.
3.
the act of appointing summarily (with or without the appointee's consent).

Also: cooptation