Latin term (English 'commensal') used of the sons of noblemen and gentry who were placed in the charge of a monastery for education in the 15-16c. Another and earlier practice was to place the son in the house of a great ecclesiastic or other magnate to learn the ways of a great house and how to be a gentleman. It was not uncommon for them to serve at table. Fees were paid, esp. if the boy was sent to a monastery. [< Lat. com- = with + mensa = table; thus to eat at the same table] -
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.