Why is the ninth month called September?
fem. proper name, a form of Elizabeth that seems to have developed in Provence. A popular name in Middle Ages; pet forms included Ibb, Libbe, Nibb, Tibb, Bibby, and Ellice. The Spanish form was Isabella, which is attested as a color name ("greyish-yellow") from 1600; the Isabella who gave her name to it has not been identified. Related: Isabelline.