TITLE: What does **Ens** stand for?
QUESTION [17 upvotes]: 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.

REPLY [14 votes]: It stands for "ensembles". Here is the other question, btw.