Nyudo Shinno (Priestly Imperial Prince) (入道親王)
Nyudo Shinno means an Imperial Prince who has entered the priesthood, becoming a lay Buddhist (Ubasoku).
In contrast, Imperial family members given the title of Imperial Prince by the Emperor after already having entered the priesthood were called Hosshino (Cloistered Imperial Prince). In the chapter 'Fujigoromo' in "Masukagami" (The Clear Mirror), there is an article on Imperial Prince Morisada who was a Nyudo Shinno (Priestly Imperial Prince).