Characterized by or producing harsh, discordant sounds; clashing or disagreeing in tone.
From Latin dissonus (dis- 'apart' + sonus 'sound'). This is an older variant form of 'dissonant' that uses the root sonus directly instead of the participle form.
Latin roots give English multiple ways to say the same thing—'dissonous' and 'dissonant' mean the same but come from slightly different Latin forms, and 'dissonant' won the popularity contest completely.
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