The term "plain clothes" refers to attire worn by law enforcement officers or military personnel that doesn't indicate their specific position or authority. Some synonyms for plain clothes include undercover clothing, street clothes, casual wear, civilian attire, everyday clothes, regular clothing, and informal garb. These terms highlight the intention to blend in and go unnoticed. In addition to law enforcement, people in other professions may also refer to non-uniform clothing as plain clothes, such as teachers or other professionals who don't wear a specific uniform. While synonyms exist, the term plain clothes is still commonly used and well-known in many settings.