coöpt

 To choose or elect in concert with another.  [1913 Webster]

 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]

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

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

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

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