From Germanic aud meaning 'wealth, prosperity'; borne by a medieval Alsatian saint.
Ottilia traces its lineage to the Old High German element *aud* or *od*, signifying wealth, fortune, and prosperous inheritance — the same root that gives us Odile, Ottilie, and the medieval name Oda. The *-ilia* suffix lends it a Latinate, almost Roman elegance, and it was under exactly this form that the name achieved its greatest historical moment: Saint Odilia of Alsace, born around 660 AD, is venerated as the patroness of the Alsace region of France. Legend holds that she was born blind and received her sight — along with her Christian baptism — through a miraculous intervention.
She founded the great double monastery of Hohenburg (now Mont Sainte-Odile) on a rocky Vosges mountaintop, which remains a pilgrimage site to this day. Through the medieval period Ottilia and its variants circulated through the German-speaking aristocracy, carried by the prestige of the Alsatian saint and by the enduring appeal of the *aud*-wealth root. It appears in the records of Holy Roman noble houses and in the baptismal registers of Swiss and Bavarian villages.
The name was never common in the English-speaking world, which is why it carries a whiff of the Continental — learned, perhaps, from a great-aunt's correspondence or discovered in the genealogical records of a Bavarian village. Ottilia today is extraordinarily rare in the United States but has a small, devoted following among parents drawn to medieval feminine names with legitimate historical depth. Its nickname possibilities — Tilly, Tillie, Otti — are warm and approachable, making it one of those names that functions as a secret kept between the birth certificate and the playground.