Big or Bad?
Enormous—very big. Compared to a flea, an elephant is enormous.
Enormity—very bad, especially in violation of morals. The enormity of child abuse is comparable to the enormity of spousal abuse.
Don’t use “enormity” when you are talking about size! “Enormity” is a noun, “enormous” is an adjective. If you need a fancy noun for “enormous,” use “immensity.” (If you need a fancy adjective for “enormity,” use “egregious.”)
Ummm…but how about the enormity of a thing? Isn’t that it’s size?
It’s grammatical, but it doesn’t mean size here, either. Still refers to badness. I agree it feels like it ought to refer to size. That’s why so many people get it wrong. The word enormity came first, even. It goes back to the 1400’s. first use of “enormous” is in the 1500’s. Both are from the same root, by the way: e(x, standing out from), +norm-(normal, the rule)+inflectional endings.