Fitz was a patronymic indicator used in Anglo-Norman England to help distinguish individuals by identifying their immediate predecessors. Meaning "son of", it would precede the father's forename, or less commonly a title held by the father. In rare cases it formed part of a matronymic to associate the bearer with a more prominent mother. Convention among modern historians is to represent the word as fitz, but in the original Norman French documentation it appears as fiz, filz, or similar forms, deriving from the Old French noun filz, fiz, meaning "son of", and ultimately from Latin filius (son). Its use during the period of English surname adoption led to its incorporation into patronymic surnames, and at later periods this form was adopted by English kings for the surnames given some of their recognized illegitimate children, and by Irish families when anglicizing their Gaelic patronymic surnames.
