decorous (adj.)

1660s, "suitable, appropriate;" 1670s, "characterized by or notable for decorum, formally polite and proper," from Latin decorus "becoming, seemly, fitting, proper," from decus (genitive decoris) "an ornament," "to decorate, adorn, embellish, beautify," from PIE root *dek- "to take, accept" (on the notion of "to add grace"). Related: Decorously; decorousness.