Fetish of an adult head inside a vagina. Term was created a few decades ago when the fantasy of unbirthing was broken down into total and partial types with partial unbirthing being the only remotely possible form of the unbirthing fantasy. Even then it is an extremely rare activity and the practice of partial unbirthing, as opposed to the fantasy, is not a form of Vore.
See a google search for partial unbirthing
by A. Akam September 23, 2007