"Guerrilla" is a word in ENGLISH

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

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.

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