The opposite of "equal" is "unequal", yet there is no word "unequality". Why do we use "inequality" instead?

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    BTW, "inequal" exists in the dictionary, marked as obsolete. Mar 9, 2011 at 19:15
  • Blocking stopped unequality getting popular, interesting, but I guess my take on the question is why did we english not take up the then obvious inequal? We are using inequality, as you say, taken up from back when, so then why not keep the consistency when not being equal and say inequal?
    – user67859
    Mar 5, 2014 at 17:36

1 Answer 1


The prefixes in- and un- both have the effect of negating the meaning of the word. The prefix in- comes from Latin and almost exclusively applies to words borrowed from Latin, which in many cases were borrowed from Latin with the in- prefix already attached. The prefix un-, on the other hand, is a native English prefix, and so, in general, can apply to any English adjective.

The Online Etymology Dictionary tells us that inequality was borrowed from Latin (via French) with the prefix in- already attached, so we get the word with the prefix in-:

1484, "difference of rank or dignity," from O.Fr. inequalité (14c.), from M.L. inæqualitas, from inæqualis "unequal," from in- "not" + æqualis "equal"

The word unequal, on the other hand, does have the same Latin root of æqualis, but the prefix un- doesn't seem to have been applied to it until after it became an English word.

There exists this phenomenon called blocking, where two seemingly equally valid ways of saying something conflict, so the existence of one blocks the other. Since the word inequality already existed from having been borrowed from French with the negative prefix already attached, the process to form the word unequality was blocked. The word unequality does exist though, but its usage is far eclipsed by inequality.

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    Blocking is an interesting phenomenon, especially since it happens in some cases but not in other. I wonder what causes some instances to have a blocking variant while in others several variants may peacefully coexist... Mar 10, 2011 at 0:09
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    So "blocking" isn't because the word form was already used to mean something else, but rather that there was already a word that means that, so there is no point making up another word to mean the same thing, even if it would make the language more consistent? +1 answer.
    – mgiuca
    Mar 16, 2011 at 1:22
  • "Inequal"? That's unpossible! :-)
    – user45532
    Jan 23, 2017 at 2:38

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