To work together, especially in a joint intellectual effort.
To cooperate treasonably, as with an enemy occupation force in one's country.
[Late Latin collabōrāre, collabōrāt- : Latin com-, com- + Latin labōrāre, to work (from labor, toil).] col·lab'o·ra'tion n., col·lab'o·ra'tive adj., col·lab'o·ra'tor n.