militancy

Concise Oxford English Dictionary © 2008 Oxford University Press:
militant/ˈmɪlɪtənt/

▶adjective favouring confrontational methods in support of a cause. ▶noun a militant person.

– derivatives
militancy noun,
militantly adverb.

– origin ME (in the sense ‘engaged in warfare’): from OFr., or from L. militant-, militare (see militate).