Nocuous is a word that describes something harmful or toxic. There are many synonyms for nocuous, depending on the context in which it is being used. For example, the word dangerous is often used interchangeably with nocuous, as both words indicate a significant potential for harm. Other synonyms for nocuous include poisonous, harmful, injurious, detrimental, deleterious, and noxious. Each of these words indicates some form of harm or danger, but may be used with slightly different connotations depending on the situation. Ultimately, the choice of synonym for nocuous will depend on the specific context and intended meaning of the word.