When someone disapproves of an action or behavior, it could be called "frowned on." However, there are numerous synonyms for this phrase. "Discouraged," "reprimanded," "condemned," "objectionable," "disapproved," "dissuaded," and "prohibited" could all be used depending on the context. If a specific group or organization opposes something, it could be said to be "opposed" or "denounced" by them. If someone wants to express their strong disapproval or opposition to an act, they could use "criticized," "chastised," or "rebuked." All of these synonyms convey a sense of negativity or rejection towards a particular action or behavior.