- There were no two ways about it -> there were two ways about it.
- Inadvertently -> advertently.
- Misnomer -> nomer.
- Unrequited -> requited.
In general, these words and phrases formed by back-formation are not recognized as standard English. A native English speaker will see “gruntled”, have to pause for a moment, and consider that it must mean the opposite of “disgruntled”. Native English speakers will not use the world “gruntled” in conversation or writing unless they are doing it for comedic effect.
These aren't (at least for the most part) back-formations but resurrections of obsolete words, though not necessarily in English. This may not be the caee for multi-word idiomatic phrases (e.g., "make no bones about").
With one exception (requited) I disagree. These are back-formations. Back-formation describes the process, if the results (coincidentally) match some plausible alternative etymology then that’s not evidence that the alternative etymology is correct! If you turn to the OED as a reference, you’ll see that it has an entry for gruntled—and it is listed as a back-formation from disgruntled; I believe it was coined by PG Wodehouse in the 1930s. The prefix dis- in gruntled is an intensifier anyway, so by constructing “gruntled” as an antonym of “disgruntled” you are not getting the original meaning back (the same dis- appears in discombobulate).
Back-formation is just a process. If a language has a word that sounds like “prefix-X”, then back-formation is the process of creating the word “X” from it. Dis- is often a Latinate prefix meaning “apart”, “removal”, or “negation”, but in the case of dis-gruntled and dis-combobulate means “completely”, so the process of adding dis- and then removing dis- has changed the meaning of “gruntled”. It is therefore a new word (if it were the same word, it would have the same meaning).
Another problem is that the imported word may have changed in meaning. “Nonchalant” may have Latinate origin if you dig deep enough, but we really took it from the French nonchaloir to disregard and French indeed has the (uncommon) chaloir to regard. However, the English word “nonchalant” does not have the same meaning as the French word “chalant”—in English it is a feeling or attitude—so when you rip the non- prefix off you are not in any sense getting something that approximates the French “chaloir” that “nonchalant” was created from in the first place.
A final problem is that the affix may not exist in the first place. “Choate” is simply nonsense, “inchoate” comes from the Latin “incohare” which means to begin and there’s simply no affix to remove.
If you have a mathematical mind, think of it as non-commutative. You can add a affix, and you can remove an affix, and you can borrow the word into another language, but these are not commutative operations and the order in which you do things changes them.
The verb “requite” and the adjective “requited” are quite normal English words, and “unrequited” is derived from them in the normal way.
“Unrequited” may be the form most commonly encountered (“mutual” is most common in many places “requited” would naturally fit), but the other forms are not neologisms created by backformation.
https://en.wikipedia.org/wiki/Back-formation
Examples from the article:
- Disgruntled -> gruntled.
- Nonchalant -> chalant.
- Make no bones about it -> make bones about it.
- Traveling incognito -> traveling cognito.
- There were no two ways about it -> there were two ways about it.
- Inadvertently -> advertently.
- Misnomer -> nomer.
- Unrequited -> requited.
In general, these words and phrases formed by back-formation are not recognized as standard English. A native English speaker will see “gruntled”, have to pause for a moment, and consider that it must mean the opposite of “disgruntled”. Native English speakers will not use the world “gruntled” in conversation or writing unless they are doing it for comedic effect.