Emily Dickinson Lexicon

IN-DE-CO'RUM, n. [L. in and decorum.]

Impropriety of behavior; that in behavior or manners which violates the established rules of civility, or the duties of respect which age or station requires; an unbecoming action. It 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.