The word "more improprietous" means something that is even more improper or inappropriate. Some antonyms for this phrase include proper, appropriate, decorous, suitable, fitting, becoming, and seemly. When discussing behavior or actions, these words can imply that the subject in question is appropriate or fitting for a particular setting or occasion. For example, proper etiquette might dictate that certain clothes or behaviors are suitable for a formal dinner party, while more relaxed behavior is more appropriate for a casual get-together. In contrast, "more improprietous" behavior might refer to actions or behaviors that are inconsiderate, disrespectful, or even offensive.