Latin

Latin is the language of the Romans brought to England. There are several Latin inscriptions and phrases seen and heard throughout Arthur's journey. Latin signs could be seen as far as Jerusalem.
*Liber ex Doctrina, the name of the book, means "book from knowledge" (but also, "free from knowledge")
*Britannia Australis (Southern Britain), seen on Merlin's map
*Memento mori (remember of death), a phrase referred by Merlin when examining the skulls on the Glastonbury Tor ruins.
*In vino veritas (truth in wine), spoken by the Mad Monk as his final words when killed by Arthur.
*Arma (weapons), sign over Mohammed's shop.
*Fictilia (earthenware vessels), over Farabi ibn Khalid's shop.
*Cetarius (fishmonger), over Hayyam ibn Aziz's shop.
*Horreum (storehouse, barn), over Ali ibn Abdullah's shop.
*Caupona (inn, tavern, lodging-house), over the Star of Allah.
*Textilia (woven textiles), over Ibrahim ibn Bushir's shop.
*Lucernae (lamps), over Tariq ibn Rashid's shop.
*Tabulae Lanius (butcher of the block [this is obviously intended to mean "butcher's block"]), over Fawaz ibn Nafi's butchery
*Antiquarius Rex (antiquarian king), over Ismail ibn Hamid's antiquities shop.
*Pro bonum tempum appella Berta (for a good time call Berta), graffitti in the alley behind the Street of David.