Science and medicine are full of Latin phraseology. Sure, I have to say these words on a day-to-day basis to communicate with my peers. But to sound like a real Ass, I could also start throwing these around in general conversation:
1. A priori/a Posteriori/ad hoc
You think that shirt will look nice with those pants? That is a priori knowledge, you better try it on first.
2. bona fide
That taxi driver was a bona fide jerk.
3. ad infinitum
I am going to listen to this album ad infinitum.
(see also: ad nauseum)
4. de facto
It may look like yellow syrup, but it is de facto cheese.