Castle or not?

Bamburgh CastleWe accept castles were military buildings. But the strange fact is that medieval people did not use the term, and nor was there a single term to describe the buildings they built and used.
Twelfth century words included: chastel,(Fr) castellum, arx, mota, turris, oppidum, munitions, firmitas and municipium (all Latin). Sometimes, we use one of the rare medieval terms today without realising we are doing so. London’s castle is called The Tower of London; and the name comes from its medieval name Turris Londiniensis.

Nowadays, some people talk of Real Castles when they mean a private and fortified residence of a lord. When that term is used, then other castles have to be given another name, or else be deemed a fake. The Anglo-Saxon chronicler who wrote of Dover’s castellein 1051, before the Norman conquest, and before the introduction of feudalism and the  concept of “castle,” was actually talking about what should technically be called a fortified settlement or burh.
Modern historians also talk of castles of display, or chivalric castles and they mean buildings that have crenellations but no proper fortifications. These,  Goodall says, are the castrati among castles– appealing but singing in the wrong register.
There’s also the confusion about manors, which are also seats of lordly authority. When is a manor distinct from a castle? Again there is confusion. In 1521 the Duke of Buckingham’s new residence was described as the manor or castell. Sir John Paston’s will dated 31/10/1477 refers to Caister in Norfolk, usually called a castle as “my seid maner and fortresse.”
But whatever the correct technical term, the medieval and early modern nobility of England occupied buildings we call castles, and from 1066 to 1640 a nobleman without a castle was like a knight without a horse.