Frowstier is an adjective used to describe a stuffy or stale environment that lacks proper ventilation. Some synonyms for this word include the following: airless, musty, stale, suffocating, oppressive, stifling, and close. Other related words that can be used as synonyms for frowstier include stuffy, dusty, and unventilated. These words all describe environments that are lacking in fresh air and can often be unpleasant to spend time in. It is important to identify and avoid these types of environments in order to promote good health and well-being. By using these synonyms, individuals can more effectively communicate the conditions of such environments.