"Poisonous gas" is a term often used to describe gases that are harmful to living organisms. However, there are many synonyms for this term that can be used to describe different types of toxic gases. For example, some gases may be referred to as "noxious gases," while others may be called "toxic fumes" or "deadly vapors." Other synonyms may include "noxious vapors," "noxious odors," or simply "toxins." Regardless of the specific term used, it is important to identify and understand the potential dangers associated with these types of gases in order to ensure the safety and well-being of those exposed to them.