The opposite of un-harmoniousness is harmoniousness, which refers to the state of being in agreement or concord, characterized by a pleasant combination of musical notes or elements. This term implies an atmosphere of peace, tranquillity, and unity. Another antonym for un-harmoniousness is agreement, which indicates that individuals involved in the situation are aligned in their thoughts, feelings, and opinions. Additionally, consonance is the opposite of un-harmoniousness, denoting agreement or compatibility in a situation or relationship. These antonyms allude to the existence of order or symmetry, as well as the absence of discord or conflict.