Ode to the OED

I love the Oxford English Dictionary. Thanks to my assocation with various academic institutions throughout the past seven years, I've had access to the online version pretty much non-stop. It's a great resource.

However, it seems to have failed me here. Or maybe I'm just confused. I swear that one of my professors spent a great deal of time discussing the "epistomological implications" of something last week. But here's the closest I could get to a definition of that first word:

episotome (n.)
[ad. mod.L. epistoma, f. Gr. upon + mouth.]
An appendage in front of the mouth in Crustacea and certain insects. Also applied to similar parts in arachnids, molluscs, etc.

Now I might be missing something pretty big here, but I highly doubt this professor was talking about the effects rendered on the study of the self by those little pincher-type things crabs have in their mouths. That's just silly.

So where have I gone wrong? I'm pleading for some help. Write comments, email me, anything. Make me smarter, people.