'co-option' definitions:

Definition of 'co-option'

(from WordNet)
noun
The selection of a new member (usually by a vote of the existing membership) [syn: co-option, co-optation]
noun
The act of appointing summarily (with or without the appointee's consent) [syn: co-option, co-optation]

Definition of 'co-option'

From: GCIDE
  • co-option \co-option\ n. same as co-optation. [WordNet 1.5]