Definitions of war:

• noun:   a concerted campaign to end something that is injurious

  Example: "The war on poverty"

• noun:   the waging of armed conflict against an enemy

  Example: "Thousands of people were killed in the war"

• noun:   an active struggle between competing entities

  Example: "A price war"

• noun:   a legal state created by a declaration of war and ended by official declaration during which the international rules of war apply

  Example: "War was declared in November but actual fighting did not begin until the following spring"

• verb:   make or wage war
• name:  A surname (very rare: popularity rank in the U.S.: #66611)