What does **Ens** stand for? Earlier someone was asking about the category "Ens" described in _Categories for the Working Mathematician_. My question is more basic: What does Ens stand for? Most of the categories have names that are self explanatory, and maybe this one does too. But for the life of me I can't think of it, and a Google search was no help.

It stands for "ensembles". Here is the other question, btw.