the invention of a new word on the assumption that a familiar word is derived from it. The verbs edit and burgle were so created from editor and burglar
2.
a word formed by this process
back-formation in American English
(ˈbækfɔrˌmeɪʃən)
noun
1.
a word actually formed from, but seeming to be the base of, another word (Ex.: burgle from burglar)