militant

adj

1. Fighting or disposed to fight; belligerent, warlike.

   “The upper tiers of the foreign ministry were quick to embrace a militant policy.”

   “Senior members of Jemaah Islamiyah, the Southeast Asian militant network blamed for the deadly Bali bombings, have announced they are disbanding the group, according to a report by a Jakarta-based think tank on Thursday.”

2. Aggressively supporting of an idea, group, political or social cause, etc.; adamant, combative.

   “The physiological state is not itself militant against erotic expression.”

noun

1. (obsolete)A soldier, a combatant.
2. An entrenched or aggressive adherent to a particular cause, now especially a member of a particular ideological faction.

   “[Jim Owles] lamented the declining influence of militant organizations and tactics, stating that militants "help keep the rest of us honest," and prevent moderates from selling out.”

   “Described by witnesses as a keen cricketer and pubgoer until contacts with Islamic militants radicalized him on a trip to Pakistan, he was ordered to serve at least 14 years for the plot, and for supplying militants in Afghanistan with money and equipment.”

   “Officials in Pakistan have confirmed that at least 250 schoolchildren between 12 and 18 years old and several teachers were taken hostage by at least seven militants inside a high school in Domail.”

3. (specifically)Someone who supports the Trotskyist political view expressed in the newspaper Militant.