in·de·co·rum \|ində̇|kōrəm, -dē|k-, -kȯr-\noun Etymology: Latin, neuter of indecorus indecorous 1.: something (as an action) that is indecorous : an offense against decorum < an indecorum for which she refused to forgive him > 2.: the quality or state of being indecorous : lack of decorum : impropriety < the general indecorum of their lives — Lionel Trilling >