back-formation

back-for·ma·tion or back formation (bkfôr-mshn)

n.

1. A new word created by removing an affix from an already existing word, as vacuum clean from vacuum cleaner, or by removing what is mistakenly thought to be an affix, as pea from the earlier English plural pease.

2. The process of forming words in this way. See Note at baby-sit.

Thesaurus

Noun

1.

back-formation - a word invented (usually unwittingly by subtracting an affix) on the assumption that a familiar word derives from it word - a unit of language that native speakers can identify; "words are the blocks from which sentences are made"; "he hardly said ten words all morning"