na-adjective, noun
Describes sexually improper or indecent behavior, speech, or content. Can be used for both people and things.
彼はみだらな冗談ばかり言う。
He always tells lewd jokes.
その映画にはみだらなシーンが多すぎる。
That movie has too many obscene scenes.
The historical derivation is uncertain. The kanji 淫 and 猥 both carry meanings related to indecency or excess, and are conventionally associated with this word.