belles-lettres

詳細解釋：

belles-let.tres

pl.n.(used with a sing. verb)（複數名詞）（與單數動詞連用）
Literature regarded for its aesthetic value rather than its didactic or informative content.
純文學：注重其美學價值而非說教或教育內容的文學
Light, stylish writings, usually on literary or intellectual subjects.
美文學：通常關於文學或智力主題的輕快、時髦的文體

來源：
French
法文
belles [fine]
belles [美好的]
lettres [letters, literature]
lettres [書信，文學]