Antonyms (opposite meanings):
* Harmony: A pleasing combination of sounds.
* Melody: A sequence of musical notes that is pleasing to the ear.
* Euphony: A pleasing or harmonious sound.
* Silence: The absence of sound.
* Tranquility: A state of peace and quiet.
Synonyms (similar meanings):
* Discord: Lack of harmony or agreement.
* Dissonance: A harsh and disagreeable combination of sounds.
* Noise: Unwanted sound.
* Ruckus: A noisy commotion.
* Din: A loud, confused noise.
The best choice of synonym or antonym will depend on the specific context in which you are using the word "cacophony."