noun, na-adjective
Refers to a lack of harmony, whether in music (dissonance) or in relationships/opinions (discord). Often used in formal or abstract contexts.
その和音には不協和が感じられる。
You can feel dissonance in that chord.
両者の意見には不協和が生じている。
Discord has arisen between their opinions.
不協和音 specifically refers to a dissonant musical chord or sound, while 不協和 can be used more broadly for discord in non-musical contexts.
Compound of 不 (fu, 'not') + 協和 (kyōwa, 'harmony, concord'). 協和 itself is from 協 (kyō, 'cooperate') + 和 (wa, 'peace, harmony').