nocternal Posted in N Best definition nocternal A person who refuses to sleep at night. Usually do to the fact that they sneak out and molest young boys. Robbie is always molesting young boys and never has time to sleep at night. I think he’s a nocternal. How satisfied are you with the definition? Looking for nocternal meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 86 times.