Seeded grapes are actually seedless

An inflammable object is really flammable

It seems to me that, superficially, the use of those affixes make the words sound like they should be antonyms, but they are not. Is this an actual thing, or just a quirk that has creeped in over time?

In addition, does this occur in languages other than English?

  • 3
    Valuable/invaluable though not truly synonyms are often used as such. Jul 20, 2012 at 19:15
  • 2
    Note that the in- in inflammable is not the negation prefix but a verbal prefix cognate with the preposition in. inflammable can be glossed as "set-into-flames-able". Feb 6, 2020 at 11:12
  • flammable is largely a 20th century word, deliberately encouraged to reduce any confusion over the meaning of inflammable.
    – Henry
    May 19, 2020 at 9:21

4 Answers 4


Transitive seed is one of those zero-derived verbs that can be either

  • Privative -- 'remove seeds from X' -- He seeded the pepper before slicing it.


  • Provisional -- 'provide X with seeds' -- He seeded the lawn before watering it.

See this linguistics problem for more examples.

  • 3
    I love contronyms.
    – acattle
    Jul 21, 2012 at 1:57
  • 4
    Where in this answer is the answer to the question (to that asked in the headline of the question, anyway)? Dec 21, 2014 at 22:24

I once posted an answer on English Language & Usage about this, I'll paste it below the line.

By the way, I couldn't find any example in other languages, so I'm not sure whether they exist or not, and I'm tending to "no".

It seems they are called Unpaired Words (maybe the best definition) or Absent Antonyms.

Unpaired Words
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. Many unpaired words are the result of one of the words disappearing from popular usage, though others were never part of a pairing and just begin with the same letters as used in common prefixes. The classification of a word as “unpaired” can be problematic, as a word thought to be unattested might reappear in real-world usage

You can find some examples here, but I'll list the majority of them here anyway for easy reference.

  1. Words with no positive forms:
    Debunk; defenestrate; dejected; disconsolate; disdain; disgruntled; dishevelled; dismayed; disrupt; feckless; gormless; impetuous; impromptu; inane; incessant; inchoate; incognito; incommunicado; indomitable; ineffable; inept; inert; infernal; inhibited; insidious; insipid; insouciant; intact; invert; misgivings; misnomer; nonchalant; noncommittal; nondescript; nonpareil; nonplussed; unbeknownst; ungainly; unswerving; untold; untoward.

  2. Words with uncommon positive forms:
    Disarray; disconcerting; immaculate; impeccable; inadvertent; incapacitated; incorrigible; inevitable; innocent; inscrutable; insensate; insufferable; interminable; unbridled; unflappable; unfurl; unkempt; unmitigated; unrequited; unruly; unthinkable; unwieldy.

  3. Suffixes (asterisk means "word not existing"):

    • Reckless/*Reckful
    • Indefatigable/*defatigable -> fatigable
    • Flammable-Inflammable (not antonyms)
  • in French, immaculé has it's strong opposite which is maculé: full of stains... immaculé being without any stain. Ethymology Latin macula, maculae: stain Jul 21, 2012 at 4:58
  • They definitely exist in other languages (what an odd conclusion to come to that they wouldn't exist in any of the 7000 languages just because you couldn't find any). E.g. the Norwegian prefix u- is used to make antonyms like un- in English, but uhumsk has no positive, uforbederlig has a very uncommon positive, while misjamn and umisjamn are synonyms (cf. flammable/inflammable).
    – unhammer
    May 30, 2023 at 15:12

There are several case like this in Hebrew, e.g., לשרש means "to uproot", but according to the regular rules should have meant "to strike roots"


Perhaps you're thinking of auto-antonyms or Janus words?

Also, Japanese has some of these, for instance "yabai" can mean either dangerous or can be used as an expression of awe. There are also some that are used primarily in British English, but not American, like "chuffed." And one that confused me for a LONG time: in England "quite" means not very much, but in American it means a lot.

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