can also be used disapprovingly to mean to cooperate with or willingly assist an enemy of ones country and especially an enemy who occupies it during a war.
Cooperate traitorously with an enemy
means to work jointly with others or together especially in an intellectual endeavor.
to work jointly with others or together esp in an intellectual endeavor [v COLLABORATED, COLLABORATING, COLLABORATES]
to work jointly with others or together especially in an intellectual endeavor.
Work jointly on an activity, esp. to produce or create something
