decorate:  Decorate comes from Latin decorātus, the past participle of decorāre ‘make beautiful’, a verb derived from decus ‘ornament’. Its root, decor-, also produced the adjective decorus ‘beautiful, seemly’, from which English gets decorous  and, via its neuter singular form, decorum . Décor is a 19th-century borrowing from French, where it was a derivative of the verb décorer. From the same ultimate source come decent and dignity. => decent, dignity, decorous
early 15c., from Latin decoratus, past participle of decorare "to decorate, adorn, embellish, beautify," from decus (genitive decoris) "an ornament," from PIE root *dek- "to receive, be suitable" (see decent). Related: Decorated; decorating.