Applications :: Is There A Medical Dictionary For OSX

I am a college student who has just started into the medical field, and I am wondering if there is a plugin for Dictionary or another application entirely that would allow me to have a Medical Dictionary on my computer?

I do not really need something with definitions, I just need something that can handle my spell checking for my weekly papers that I need to hand in.

I realize that this is probably not the best place to ask, but the people who I asked in my class including my instructor said that I am pretty much out of luck unless I just want to search each one through a website.

What I would love is if there is something that would work with Pages, but I will live with Word if one exists.