v. t. [ See Cooptate. Cf. F. coopter. ] To choose or elect in concert with another. [ R. ] [ 1913 Webster ]

Each of the hundred was to coopt three others. Jowett (Thucyd.). [ 1913 Webster ]

2. To choose or elect as a colleague or fellow member of a group; as, The church members co-opted individuals from similar backgrounds to replenish the congregation. [ PJC + WordNet 1.5 ]

3. To assimilate (a smaller group) into a larger group. [ PJC ]

4. To persuade an opponent to join one's own side. [ PJC ]

5. To appoint summarily (with or without the appointee's consent). [ WordNet 1.5 ]

6. To appropriate (something rightly belonging to another) as one's own; to preempt; as, to co-opt someone's name. [ PJC ]

v. t. [ L. cooptatus, p. p. of cootare to elect to something; co- + optare to choose. ] To choose; to elect; to coopt. [ Obs. ] Cockeram. [ 1913 Webster ]

n. [ L. cooptatio. ] The act of choosing; selection; choice. [ Obs. ] [ 1913 Webster ]

The first election and cooptation of a friend. Howell. [ 1913 Webster ]

2. the selection of a new member (usually by a vote of the existing membership). See co-opt{ 2 }.
Syn. -- co-option. [ WordNet 1.5 ]

3. the act of appointing summarily (with or without the appointee's consent).
Syn. -- co-option. [ WordNet 1.5 ]