cooperate

To work or act together, especially for a common purpose or benefit.

In polling by the Pew Research Center in November 2008, fully half the respondents thought the two parties would cooperate more in the coming year, versus only 36 percent who thought the climate would grow more adversarial.

To allow for mutual unobstructed action.

To function in harmony, side by side.

To engage in economic cooperation.

To obtain the cooperation of (a potential witness); to turn (someone) into a cooperating witness.