back-form

If affixation means forming a word by adding an affix (e.g. frosty from frost, refusal from refuse, instrumentation from instrument), then back-formation is essentially this process in reverse: it adapts an existing word by removing its affix, usually a suffix (e.g. sulk from sulky, proliferate from proliferation, back-form from back-formation).

Back-forming back-formations 2009

If affixation means forming a word by adding an affix (e.g. frosty from frost, refusal from refuse, instrumentation from instrument), then back-formation is essentially this process in reverse: it adapts an existing word by removing its affix, usually a suffix (e.g. sulk from sulky, proliferate from proliferation, back-form from back-formation).

April « 2009 « Sentence first 2009

But the adjective ginger has been obsolete for a long time, and it's notable that nobody is tempted to back-form it anew, as in "his ginger handling of the question," which is what you'd expect if the adverbial gingerly were really analyzed as composed of the root ginger plus the derivational suffix -ly.

languagehat.com: GINGER(LY). 2004

When my evening-school had been in operation a few weeks, I noticed, one evening, at the end of the back-form on the girls 'side a new face.

The Atlantic Monthly, Volume 13, No. 78, April, 1864 Various

On several occasions, when some unusually intelligent little creature would come from a back-form, and solve a question which had bewildered those in front, there was a sensible expression of delight over the whole school.

Chambers's Edinburgh Journal, No. 426 Volume 17, New Series, February 28, 1852 Various 1836

Interestingly, if you back-form ‘disappointed’, you change its meaning substantially enough to make it entirely inappropriate: “Winter’s piece appointed me …”

Back-forming back-formations 2009