Nosey

[Mrs.Claim]

What is the medical term for someone who is too nosey?

[Quizmonster]

Such unnatural needs are called 'philias' and their names are made up from the appropriate Greek root-word with some element of 'philia' tacked onto the front or back.
Greek for 'knowledge', which is what a nosey person likes to get hold of, is 'gnosi', so how about 'gnosophile'? It has the added attraction of actually sounding like 'nosey', being pronounced nose -o - file.