/ ˈwɔːfeə(r); NAmE ˈwɔːrfer/ noun [ U ]
1.
the activity of fighting a war, especially using particular weapons or methods :
air / naval / guerrilla, etc. warfare
countries engaged in warfare
—see also biological warfare , chemical warfare , germ warfare
2.
the activity of competing in an aggressive way with another group, company, etc. :
class / gang warfare
The debate soon degenerated into open warfare.
—see also psychological warfare