- 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 war of words; a price war.
- A concerted effort or campaign to combat or put an end to something considered injurious: the war against acid rain.
- 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.