war

A state of open, armed, often prolonged conflict carried on between nations, states, or parties.

The period of such conflict.

The techniques and procedures of war; military science.

A condition of active antagonism or contention.

A concerted effort or campaign to combat or put an end to something considered injurious.

To wage or carry on warfare.

To be in a state of hostility or rivalry; contend.

(at war) In an active state of conflict or contention.