Of, or relating to, a Medieval social structure where, in theory, the nobility would protect everyone, the peasants would pay for this protection by working the land, and the clergy would pray for everyone. In the secular world, the monarch was at the top of the pyramid, with each layer of nobility and commons owing services or favour to the layers above and below them. Although the term relates to the Middle Ages, it was not actually coined until the 16th century, so some medievalists don't like it.
Fact of the Day
The earliest book of English table manners was written by Daniel of Beccles in the time of Henry II. It prohibited elbows on tables, talking with full mouths and scratching armpits. It also gave guidance on what to do if the wife of the host were to make a pass at a guest: he should feign illness.