Decorous :: Decorous (a.) Suitable to a character, or to the time, place, and occasion; marked with decorum; becoming; proper; seemly; befitting; as, a decorous speech; decorous behavior; a decorous dress for a judge..
Indecorous :: Indecorous (a.) Not decorous; violating good manners; contrary to good breeding or etiquette; unbecoming; improper; out of place; as, indecorous conduct..