This noun denotes obscenity, shameful conduct, or moral degradation—behavior that is disgraceful and violates proper standards. Classical usage included ugliness, deformity, and filthy conduct (euphemistically even sexual perversion). Paul uses it in Ephesians 5:4 listing things "not fitting" for believers: "obscenity, foolish talk, and crude joking." The term emphasizes the shameful, degrading nature of such behavior—conduct that contradicts the holiness and dignity of those called to be saints. It's not merely bad taste but moral pollution, behavior that debases human dignity and contradicts the purity expected of God's people.