Unallowably is an adverb that refers to anything that is prohibited, banned, or restricted by law or regulation. Some synonyms for unallowably are "illegally," "prohibited," "forbidden," "unlawfully," "unpermitted," "not permissible," and "impermissible." These words suggest actions or behavior that are wrongful or in violation of established rules and standards. Other terms that can be used in place of unallowably include "unauthorised," "unlicensed," "improper," "unacceptable," and "taboo." These synonyms can help convey the same meaning with slightly different shades of connotation, giving writers and speakers a range of options to match their specific context or tone.