The word demigod is now wide used in English because of Isckon for Hindu gods like Shiva, Laxmi, Durga, Ganesha, Kali, Surya, Kaartikeya, Saraswati etc.
Don't use it anymore. They are not demigods. First give me a sanskrit word from Vedas/Puranas/Smritis for "demigod" used for all these Gods and never used for Vishnu in the scriptures.