From where come from the term "lowering"?

[Asman01]

I was reading Walter's article where he use this term and explain 
what is it. He did a clear explanation abount what what it does. 
But where come from actually this term? I can't find anything 
related with a lot of keyword combinations on google/bing. And 
isn't only me want to know about origin of this term 
(http://stackoverflow.com/questions/20252876/wanted-good-definition-of-the-term-lowering-in-the-context-of-compilers)