Which of the titular phrase is the correct one? I find usages for both of them.

Well-formedness is the quality of a clause, word, or other linguistic element that conforms to the grammar of the language of which it is a part.


...within the final applicative expression, to check the well-formness of French negative construction.

  • 5
    I do not think well-formness is a word. Where have you found it like this? Any place that is reputable?
    – Hank
    Commented Feb 14, 2017 at 17:09
  • 3
    Well-formness is not correct. This comes from a source full of ill-formed English. Commented Feb 14, 2017 at 17:10
  • :(( for the low quality question!
    – Eilia
    Commented Feb 15, 2017 at 8:17

1 Answer 1


Well-formness is incorrect. As StoneyB points out, it comes from Combinatorial Categorial Grammar for Computer-Assisted Machine Learning, which, ironically, appears to be filled with grammar and spelling errors; I spotted at least three on that page alone.

In general English, any word of the form X-ness can be read as "the extent to which X is exemplified"*. For example, the wetness of a towel, the emptiness of space. In these cases, X denotes a property, so its part of speech has to be that of an adjective. "Well-formed" is an adjective; "well-form" is nonsense.

*There are exceptions. "Likeness" and "witness" have different etymologies, for example.

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