na-adjective, noun
Describes something sexually suggestive, morally corrupt, or decadent in a literary or formal register. Often used for atmosphere, art, or behavior.
その小説には淫靡な描写が多く含まれている。
That novel contains many obscene descriptions.
彼の淫靡な笑みが不快だった。
His lewd smile was unpleasant.
Compound of 淫 (いん, 'lewd, excessive') and 靡 (び, 'seductive, beautiful'). The exact historical derivation is uncertain, but the combination conveys a sense of decadent, alluring obscenity.