Ildo is a diminutive of Ildiko, itself most likely a Hungarian variant of Hilda. Hilda originates in Germanic languages and means "fighting a war". This was the name of a 7th century English saint, Hilda of Whitby. Throughout centuries, Hilda has been a popular name among royalty, including Princess Hilda of Nassau and others. In the English-speaking countries it has been more frequent since the 19th century.