dec·o·rous 
(dĕkər-əs, dĭ-kôrəs)
(dĕkər-əs, dĭ-kôrəs)adj.
Characterized by or exhibiting decorum; proper: decorous behavior.
[From Latin decōrus, becoming, handsome, from decor, seemliness, beauty; see dek- in the Appendix of Indo-European roots.]
deco·rous·ly adv.
deco·rous·ness n.