Product Code Database
An unpaired word is one that, according to the usual rules of the language, would appear to have a related word but does not. Such words usually have a prefix or suffix that would imply that there is an antonym, with the prefix or suffix being absent or opposite. If the prefix or suffix is negative, such as 'dis-' or '-less', the word can be called an orphaned negative.
Unpaired words can be the result of one of the words falling out of popular usage, or can be created when only one word of a pair is Loanword from another language, in either case yielding an accidental gap, specifically a morphological gap. Other unpaired words were never part of a pair; their starting or ending , by accident, happen to match those of an existing morpheme, leading to a reinterpretation.
The classification of a word as "unpaired" can be problematic, as a word thought to be unattested might reappear in real-world usage or be created, for example, through humorous back-formation. In some cases a paired word does exist, but is quite rare or archaic (no longer in general use).
Such words – and particularly the back-formations, used as – find occasional use in wordplay, particularly light verse.
| Awful | Awless | Not attested |
| Disambiguate | Ambiguate | Not attested. Disambiguate derives from dis- + ambigu(ous) + -ate in the mid-20th century |
| Discomfit | Comfit | Not an antonym. Comfit (noun) is a candy comprising a sugar-coated nut or fruit. From Old French confit, from Latin confectum meaning "put together". Discomfit probably includes some conflation with discomfort. |
| Disgruntle | Gruntle | Humorous back-formation, circa 1938. |
| Disgusting | Gusting | From Latin gustāre meaning to taste; antonym form appeared in Old French desgouster |
| Disheveled, Dishevelled | Sheveled, Shevelled | Not attested. Disheveled is from Old French deschevelé. |
| Exasperate | Asperate | Synonym. To make rough, a similar connotation to exasperate's secondary meaning of increasing the intensity of pain. |
| Feckless | Feckful | Used in Scottish English |
| Gormless | Gormful | Not attested. Gormless derives from , whose antonym is rare and highly region-specific. |
| Imbecile | Becile | Not attested. |
| Improvisation | Provisation | Not attested, as something created with forethought. |
| Impulsive | Pulsive | Rare. Means "tending to compel; compulsory". |
| Incorrigible | Corrigible | Rare. Typically describes the abstract, such as a theory, rather than a person. |
| Indomitable | Domitable | Rare |
| Ineffable | Effable | Rare |
| Inert | Ert | Not attested. Inert is from Latin iners, meaning "without skill". The corresponding Latin antonym, ars, is the source of English art, which is not an antonym of inert. |
| Inflammable | Flammable | Synonym. From Latin flammare meaning "to catch fire". Inflammable is from Latin inflammare meaning "to cause to catch fire". Antonym is nonflammable. |
| Innocent | Nocent | Rare. Means "harmful". |
| Innocuous | Nocuous | Uncommon |
| Irritate | Ritate | Not attested |
| Nonchalant | Chalant | Humorous back-formation, popularized by platforms like TikTok. |
| Noncommittal | Committal | Not an antonym. Committal (noun) means "the process of sending someone to a mental institution". |
| Nonplussed | Plussed | Not attested. Nonplussed is from Latin non plus, meaning "no more". |
| Nonsensical | Sensical | Rare. Nonsensical is derived from nonsense. |
| Off-putting | Putting | Not antonyms. |
| Overwhelm / Underwhelm | Whelm | From Middle English whelmen meaning "to turn over". May mean "to moderately impress" in recent usage. |
| Postpone | Prepone | Used in Indian English |
| Rebuttal | Buttal | Not attested |
| Reckless | Reckful | Not attested |
| Repeat | Peat | Unrelated in meaning. Means a soil formed of decomposition of plant matter. |
| Rueful | Rueless | Not attested |
| Ruthless | Ruthful | Rare. Means "full of or causing sorrow". |
| Uncouth | Couth | Rare. From Old English cunnan meaning "well-known" or "familiar". |
| Ungainly | Gainly | Rare |
| Unkempt | Kempt | Rare. Kempt was replaced by passive participle combed as comb replaced kemb. While unkempt extended to grooming and hygiene generally, combed did not undergo the same extension. Appears in the form well-kempt. |
| Unruly | Ruly | Rare |
| Unscathed | Scathed | Rare |
| Unstinting | Stinting | Rare |
| Untoward | Toward | Not an antonym. Untoward evolved from figurative alterations of toward involving deviation from norms; toward acquired no similar figurative meanings. |
| Unwieldy | Wieldy | Rare |
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