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minor; small; unimportant; obscure
minor (key, scale, etc.)
the minor leagues (US baseball)
彼の趣味はとてもマイナーだ。
His hobby is very niche.
私はマイナーなバンドをよく聴きます。
I often listen to obscure bands.
その映画祭ではマイナーな監督の作品が紹介された。
At that film festival, works by obscure directors were introduced.