Backblast is a term used to describe the blast of hot gases that can occur from the rear of certain firearms or rocket launchers. This can cause injury or damage to those standing behind the weapon. However, there are several synonyms for this term, including recoilless, blowback, and retrofire. The word retrofire is often used in the context of space travel, referring to the act of firing a rocket engine in the opposite direction of the spacecraft's motion to slow or stop its forward momentum. Regardless of the specific term used, it is important to use caution and be aware of your surroundings when operating firearms or other explosive devices.