Bashi-bazouk is a unique word that refers to irregular or undisciplined troops. However, if you are looking for synonyms to describe such troops, there are several different phrases that you can use such as mercenaries, guerrillas, insurgents, or militants. These terms describe individuals who are not officially affiliated with the military but use unconventional tactics and often cause chaos. Other synonyms include bandits, marauders, raiders, or looters. These words describe individuals who often operate outside of the law and cause destruction for personal gain rather than for any political or ideological motivation. Whatever term you choose to use, these individuals are characterized by their unpredictability and their tendency to operate outside of the established rules of warfare.