What was the gladiator training school and barracks called?

The gladiator training school and barracks were known as a "ludus." This term refers specifically to the facility where gladiators trained in preparation for their performances in the arena. In these establishments, trainers would instruct the fighters in various combat techniques, physical conditioning, and discipline necessary for their future contests.

The other terms listed do not reflect the nature of a gladiator training school. "Thermae" refers to public baths, which were places for socializing and relaxation rather than training for combat. "Colosseum" denotes the famous amphitheater in Rome known for hosting gladiatorial games, but it is not a training facility. "Domus" refers to a private residence in ancient Rome, further distinguishing it from the specialized environment required for training gladiators. Thus, the term "ludus" is the accurate designation for the training schools where gladiators prepared for their roles as entertainers and fighters.