decorous in WordNet English dictionary

1. 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"
   becoming  comely  comme il faut  decent  decorous  seemly 
   
2. characterized by propriety and dignity and good taste in manners and conduct
   "the tete-a-tete was decorous in the extreme"
   decorous