Fitz (pronounced fits) is a prefix in patronymic surnames of Anglo-Norman origin, that is to say originating in the 11th century. The word is a Norman French noun meaning son of, from Latin filius (son), plus genitive case of the father's forename.Whilst Fitz is now the standard form used by modern historians the word appears in ancient documents with various spellings such as fiz, filz, etc.uch families took their surnames from their principal manor on which they resided and which formed their seat. This was the case for example with William the Conqueror 's great noble adviser Roger de Beaumont (c.1015-1094), (Roger from Beaumont), who took his surname from his manor of Beaumont-le-Roger in Normandy.