In`de*co"rum (?), n. [Pref. in- not + decorum: cf. L. indecorous unbecoming.]
Want of decorum; impropriety of behavior; that in behavior or manners which violates the established rules of civility, custom, or etiquette; indecorousness.
An indecorous or becoming action.
Syn. -- Indecorum is sometimes synonymous with indecency; but indecency, more frequently than indecorum, is applied to words or actions which refer to what nature and propriety require to be concealed or suppressed. Indecency is the stronger word; indecorum refers to any transgression of etiquette or civility, especially in public.
© Webster 1913.