Daily Ancestorfilius
Filius is Latin for "son"; filius Petri means "son of Peter," with the father's name in the genitive case.
Filius means son. In Latin registers it usually comes right after the child's name and before the parents, as in Joannes filius Petri, John son of Peter. The plural filii means sons or children.
The father's name changes its ending (Petrus becomes Petri), which can be confusing when you copy names. Record the name in its basic form, not the ending you see after filius.
As seen in a recordBaptism entry in a Catholic parish register
Joannes, filius legitimus Petri Miller et Annae
How to cite this page
Daily Ancestor. "filius." Dictionary of Old Record Words. https://dailyancestor.com/dictionary/latin/filius. Last checked 2026-10-01.