My question is, where are we drawing the line on advanced medical terminology? What words can, and cannot be used? I understand that there comes a time when it is breaking the suspension of disbelief in a setting, however it was my understanding that the Forgotten Realms had a nearly modern(Perhaps 18th-19th century), understanding of medicine. So I would ask what that line is, if anyone could answer?

It's possible that necromancers and transmuters, and some very dedicated, learned monk- or ranger- healers, have been exposed to advanced research on human anatomy or the non-magical treatment of physical ailments.

However, even such characters would be aware that magic is often faster, safer and more easily "understood" (accepted) than "modern" methods. While there's a fairly high rate of literacy on Faerun, for the common person this is to facilitate communication and trade, not research that would most likely be conducted by people who already have all the magical resources they need to achieve the same ends. Those cultures that have rejected or cannot easily employ magical solutions most likely have folk wisdom guiding their healing, rather than medicine founded in reason.

As for what words you can/cannot use, I don't know anything about medicine. I can barely spell scalple.

No hypothermia.

I think words like hemorrhaging are already crossing the border. Healing the sick is allowed by herbal remedies, divine intervention, "MAGIC", or the primitive chase of scientific methods like trial and error. Stuff like that. I also don't think a character should be coming up with outlandish ideas like asking a cook for a cup of sugar, some boiled water, a pot with a hole, some cleaned intestine, and a hollowed needle to help stow blood loss with a makeshift IV. Be creative and come up with your own methods, but keep them in line with the environment that you're in.

Nearly modern and modern are two very different animals with reguards to medical understanding. The beginning of the 1800's still had a lot of people using cupping, bleeding, leeching, and laudinum as mainstays of therapy. Things were well named for the most part anitomically, but the understanding or physiology of the structures wasn't there. The mid 1900's had huge leaps in available applied medical theraputics but still lacked a -huge- understanding of prinicples the medical community now takes as very basic knowledge that every medical student is expected to know.

Again, really any treatment past the basics would likely be out of line with the norm. People outside of necromancers and perhaps very dedicated (to knowledge) healers would not know the terminology at all. Try to be original, and think about where you are and the setting.