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Where did prefix exceptions originate?

  • efficient
  • accessible
  • consistent
  • articulate
  • considerate
  • conceivable
  • convenient


  • inefficient
  • inaccessible
  • inconsistent
  • inarticulate
  • inconsiderate
  • inconceivable
  • inconvenient

However valuable to invaluable sits alone, like a trap, not merely an inconvenient irregularity but seemingly almost inconceivable that it's not a deliberate inconsistency, causing an inconsiderate degree of inaccessibility for the inarticulate. So English is even more inefficient and inaccessible than it would otherwise be.

Or is there a logical reason why invaluable doesn't mean unvaluable?

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    This sounds like peeving disguised as a question. – simchona Jan 7 '12 at 23:47
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    I'm natively English. I don't have a problem with the languege as a whole. I quite enjoy it although I havn't to be fair tried other languages. I just don't see the point in things like this. Also it is a question, if anyone knows why it's as it is. – alan2here Jan 7 '12 at 23:50
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    You "don't see the point" is why I think you're peeving. – simchona Jan 7 '12 at 23:53
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    The point? English isn't designed, it just kinda happens. – Matt E. Эллен Jan 7 '12 at 23:53
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    cf. flammable vs. inflammable – ThePopMachine Jan 8 '12 at 5:25

The reason for the prefix in- in invaluable is that it originally meant simply "impossible to value". It has somehow acquired the more specific meaning that it is impossible to value because its value is infinitely high. So there is no illogicality here.

Cf. innumerable, "impossible to count (because the number is infinite)", immense, "unmeasured (because it is too great to be measured)", etc. etc.

When you think about it, it is not even the word invaluable that has shifted in meaning the most, but rather valuable: it evolved from "capable of being valued" to "capable of being valued highly (because its value is high)". It is mostly the shift in the meaning of valuable that pulled the former opposites together, though I concede that invaluable bears some of the blame too.

Cf. numerous "having a high number", instead of simply "having a number", etc.

  • :¬o You'r right. Valuable should be 'able to be valued'. The modern usage is the wrong one. – alan2here Jan 8 '12 at 0:06
  • Sorry. I removed the original comment because I realised I was thinking about it wrongly. I meant 'dosn't have one' as being similar to 'not', but as you say it's not the 'in' prefix thats changed, it's the meaning of the word valuable. – alan2here Jan 8 '12 at 0:08
  • @alan2here: Agreed. But "wrong" is a bit too strong: better call it "irregular". – Cerberus_Reinstate_Monica Jan 8 '12 at 0:15

There is no inconsistency. "Valuable" means "having a value (which can be calculated)". "Invaluable" means "having an incalculable (enormous) value". The prefix "in-" refers to the calculability, not the magnitude, of the value.

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    So priceless means no price that can be calculated and worthless mean no worth that can be calculated. But it is not obvious why invaluable should mean infinite value rather than zero value. – Henry Feb 10 '12 at 14:53
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    Right, it not obvious by simply looking at the prefix. For that matter, why shouldn't "valueless" mean the same as "invaluable"? But this is a bit like asking why "cat" shouldn't mean a small rock. The answer is simply: because it doesn't. It's an accident of history. – MetaEd Feb 10 '12 at 15:31

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