A more thorough explanation:

Definition: Co-optation is the process of selecting a person to fill a vacancy, usually in a close corporation.

Example: When a board member of a company resigns, the remaining members may use co-optation to select a replacement without holding an election.

Explanation: Co-optation is a way for a small group of people, such as a board of directors, to choose a new member without involving the larger group of shareholders or members. This can be useful when a vacancy needs to be filled quickly or when the group wants to maintain control over who joins them. However, it can also be seen as undemocratic because it doesn't allow for a wider range of candidates or input from the larger group.