na-adjective, noun
boorish; tactless; unrefined; unromantic
Describes a person or action that lacks refinement, sensitivity, or romantic sensibility; often used for someone who spoils the mood or fails to appreciate subtlety.
彼の無粋な発言で場がしらけた。
His tactless remark killed the mood.
花より団子とは無粋な考え方だ。
Preferring dumplings over flowers is such an unromantic way of thinking.
Compound of 無 (without) and 粋 (refinement, chic). The exact historical derivation is uncertain, but the word has been used since the Edo period to describe a lack of stylishness or tact.