Unpaired word

An unpaired word is one that, according to the usual rules of the language, would appear to have a related word but does not.^[1] 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.^[2]

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 borrowed 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 phonemes, 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 nonce words – find occasional use in wordplay, particularly light verse.

In English

Word	Paired word(s)	Notes on paired word
Awful	Awless	Not attested
Disambiguate	Ambiguate[a]	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[b]	Humorous back-formation, circa 1938.
Disgusting	Gusting	From Latin gustāre meaning to taste; antonym form appeared in Old French desgouster
Disheveled, Dishevelled	Sheveled,[a] Shevelled[a]	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[3]
Gormless	Gormful	Not attested. Gormless derives from gaumless, whose antonym gaumy is rare and highly region-specific.
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.[citation needed]
Indomitable	Domitable	Rare
Ineffable	Effable	Rare
Inert	Ert[a]	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.[4]
Innocent	Nocent	Rare. Means "harmful".
Innocuous	Nocuous	Uncommon[5]
Irritate	Ritate	Not attested
Nonchalant	Chalant	Humorous back-formation, popularized by platforms like TikTok.[6]
Noncommittal	Committal	Not an antonym. Committal (noun) means "the process of sending someone to a mental institution".[7]
Nonplussed	Plussed[b]	Not attested. Nonplussed is from Latin non plus, meaning "no more".[8]
Nonsensical	Sensical	Rare. Nonsensical is derived from nonsense.[9]
Off-putting	Putting	Not antonyms.
Overwhelm / Underwhelm	Whelm	From Middle English whelmen meaning "to turn over".[10] May mean "to moderately impress" in recent usage.[11]
Postpone	Prepone	Used in Indian English[12]
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".[13]
Uncouth	Couth[b]	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

See also

• Accidental gap
• Back-formation
• Cranberry morpheme
• Defective verb – other form of lexical gap
• Eggcorn
• False cognate
• Fossilization (linguistics)
• Polarity item

Notes

1. Words not attested or very rare in English usage.
2. Jocular or facetious coinages as intentional back-formation.