I'd been of the mistaken belief that the term refactoring, while used in casual parlance during the 1980s, hadn't made it into print until the publication the seminal paper by Bill Opdyke and Ralph Johnson in 1990. Opdyke's 1992 thesis gave a more detailed account of this work.
Thanks to Bill Wake for pointing out this this fully-formed treatment of the style of program revision that came to be known as refactoring in his 1984 book Thinking Forth, by Leo Brodie. And right there, on page 181, is what is, to the best of my knowledge, the first published appearance of The Word itself.
Forth enjoyed a burst of popularity during the early 1980s, before the object boom. I still own a copy of Starting Forth. Alas, this is the first time I'd seen this treatment of program factoring in Thinking Forth.
Forth, of course, remains an ubiquitous part of our everyday lives, in the guise of a proprietary variant, Postscript, that hums along under the hood in so many of the world's printers (among other places).
A tip-of-the-hat to Leo, and the refactoring pioneers of Forthdom...