Cacophonous
Etymology
From Greek "kakophonia," from "kakos" ("bad") plus "phōnē" ("sound, voice"). It literally means "bad-sounding," and it names noise that is harsh and discordant — the exact opposite of euphonious.
adjective · /kuh-KOF-uh-nus/
Full of harsh, jarring, discordant sound.
What it names
The word for a clashing mixture of noises that grate on the ear — traffic, shouting, instruments out of tune.
Example
The market was cacophonous with vendors shouting over blaring radios.
Related idea
Discordant means lacking harmony, often of just a few clashing notes; cacophonous suggests a broader, overwhelming din of harsh sound.