Guerrilla

Part of speech: noun (n.)

1. An irregular mode of carrying on war, by the constant attacks of independent bands, adopted in the north of Spain during the Peninsular war.

2. One who carries on, or assists in carrying on, irregular warfare; especially, a member of an independent band engaged in predatory excursions in war time.

Part of speech: adjective (a.)

Pertaining to, or engaged in, warfare carried on irregularly and by independent bands; as, a guerrilla party; guerrilla warfare.