Dionisia

Also Corsican: http://mathieu.nivaggioni.free.fr/francis/paoli.htm

Also Galician: http://www.ige.eu/igebdt/esq.jsp?idioma=gl&ruta=onomast/nomes.jsp
https://gl.wikipedia.org/wiki/Lista_de_nomes_femininos_en_galego#I

Also Italian: https://it.wikipedia.org/wiki/Dionisia. [noted -ed]

Dionisia is indeed the medieval English form of Denise. However, today Dionisia is used in Spanish and occasionally Italian. It's Portuguese too, but it's written as Dionísia. It's these countries' equivalent of Denise.