Remember how the word “pea” came from the mass noun “pease“? This is a perfect example of back-formation. Even though the “s” at the end of pease did not actually mean plural, once this word got to English, the English speakers changed it. In English, having an -s at the end of a word makes us think it’s a plural; thus pea became the singular form. Sometimes when words are borrowed between languages, the original features of the word (like a suffix of -s) take on new meanings in the new language.

It’s usually hard to tell if a word is a back-formation just from looking at it. You might think that the word “donation” comes from the verb “donate“, but it’s actually the other way around. Donation was the original noun. Donate was back-formed from it.

Two more examples of back-formation are grovel (by Shakespeare) and sidle.  There is a pattern in English of how to form a gerund.  You add -ing to the base of a verb.  The adverbial ending -ling sounds very similar and is sometimes indistinguishable from -ing when it’s attached to a word.  Originally in English we only had the word groveling, and it was an adverb. Shakespeare probably thought that groveling was the gerund form of the verb grovel and decided to use grovel as a verb.  (Or, he knew that it was an adverb and figured it would make a nice verb anyway.)

The same thing goes for the creation of the word sidle from sideling (and/or?) sidelong.  Someone heard side-ling and broke it in the wrong place: sidel-ing.  Sidel’s spelling changed to sidle, and we were given a brand new verb via back-formation.

Some more examples of back-formation (found on Wikipedia)…

• babysit from babysitter (a verb from a noun)
• edit from editor (a verb from a noun)
• syringe from syringes (a singular form from a plural)
• euthanase/euthanize from euthanasia (a verb from a noun)
• enthuse from enthusiasm (a verb from a noun)
• resurrect from resurrection (a verb from a noun)
• sleaze from sleazy (a noun from an adjective)

Often back-formations start out colloquial and still sound strange for a while before they become commonly known words. Enthuse is still not universally accepted as a proper word.

In a sort of meta-recursiveness, the verb back-form (referring to the action of back-formation) is actually a back-formation itself. It comes from the noun back-formation. How’s that for confusing?

The word back-formation was coined in 1897 by James Murray, the founding editor of the Oxford English Dictionary. (This fact via About.com.)