The word "punchbag" is commonly used to describe a sack filled with sand or other material, which is used for practicing boxing or martial arts moves. However, there are several other synonyms that can be used to describe this type of equipment. Some of the most common synonyms for "punchbag" include heavy bag, punching bag, training bag, and boxing bag. Other commonly used synonyms include speed bag, double-end bag, and uppercut bag. Depending on the type of training or workout being performed, different types of punchbags may be used. For example, a speed bag is typically used for improving hand-eye coordination and quick movements, while a heavy bag is used for building strength and power.