I would have thought it was Einstein, or some other physicist, around 1905.
However, it was actually the distinguished chemist G.N. Lewis, as late as 1926!
I learnt this in a nice article from "This Month in Physics History" in the APS News. It also discusses Lewis' possible suicide due to depression.
On a lighter side, this reminds me of a silly achievement on my own: getting the term "squashon" into the scientific literature (see this paper from my Ph.D).