Decorous behaviour is very respectable, calm, and polite. = seemly, proper + decorously deco·rous·ly He sipped his drink decorously. having the correct appearance or behaviour for a particular occasion (decorus, from decor )
according with custom or propriety; "her becoming modesty"; "comely behavior"; "it is not comme il faut for a gentleman to be constantly asking for money"; "a decent burial"; "seemly behavior"
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