For anybody else confused by the fact that RAM is never expanded, I believe it's Random Access Machine [1]. At least, this is my conclusion after a cursory search for "oblivious RAM."

[1] https://en.wikipedia.org/wiki/Random-access_machine

Yeah, it's a model of computation used in this line of research. See the original Goldreich/Ostrovsky paper for more info: http://dl.acm.org/citation.cfm?id=233553

Shortening Random Access Machine to RAM is standard in TCS.

Transdichotomous convex sets?

Theoretical Computer Science - at least that must be standard terminology among computer scientists?!?

I've only ever seen it spelled out "theoretical CS". There is GOFAI, though.