As the OED etymology of the English word points out (Third Edition, 2011), the entry may be considered Latin rather than Anglo-Norman: not only are there the transparently Latinate forms (nominative singular in rubea and accusative singular in robeam and rubeam), but also the more Anglo-Norman looking form rubee may well be a genitive singular form of Latin rubea. However, the Anglo-Norman context suggests a certain level of vernacularisation.