Harmony is the sound of things that go together well — people singing in harmony are in tune with each other. Best friends should be in harmony most of the time if they want to stay best buds! Harmony is a noun that describes an agreement, such as in feeling, sound, look, feel, or smell. It’s necessary for roommates to be able to live in harmony in a small space, or they’re in for a wake-up call. In music, harmony is a pleasing combination and progression of chords. If it makes you wince, it’s lacking harmony. Synonyms for harmony include accord, concord, cooperation, like-mindedness, and unanimity. Antonyms, on the other hand, range from clash and disagreement to discord.