Undoubtably vs. undoubtedly

Undoubtably and undoubtedly are both well-formed words with clear, distinct meanings, yet the former is often used in place of the latter, giving rise to the mistaken belief that undoubtably is always wrong. It’s not. The distinction between them can be subtle; something that is undoubted is not doubted, while something that is undoubtable is not capable of being doubted. The two meanings often overlap, which is why mixing up the two words is often not a serious error, yet the difference is occasionally important. For example, one might claim that in his or her opinion the Beatles are undoubtably the most influential rock band in history, yet we probably couldn’t say they are undoubtedly so, because even one who believes the Beatles to be the most influential band must acknowledge that there are rock critics who doubt this.



[B]ut a double-bill featuring two of the biggest names in contemporary jazz is undoubtably a main event. [Los Angeles Times]

But another part of his reasoning is undoubtably a judgment about Obama. [Washington Post]

There will undoubtably be tougher controls on the oil industry: one revelation of the crisis has been how poorly it was regulated. [Telegraph]


17 thoughts on “Undoubtably vs. undoubtedly”

    • Undoubtably is listed in my 2006 copy of the Oxford Dictionary of English (not Oxford English Dictionary, as many seem to think), Second Edition, Revised, published by the Oxford University Press, of Great Clarendon Street, Oxford.

      It is listed as an adverb derivative of the adjective Undoubtable.

      The definition of Undoubtable, which is listed as rare, is: “not able to be doubted; indubitable”

      By subtle contrast, the definition of Undoubted is: “not questioned or doubted by anyone”

      • I stand corrected. Thank you. I found the same result as you in the online Oxford dictionaries. Dictionary dot com is awful. I will never use it again.

      • Your Oxford Dictionary of English is distinct from the Oxford English Dictionary (OED) which is far more comprehensive and detailed in its exposition of definitions, usage and etymology.
        Please don’t confuse your “school” dictionary with the real thing, the OED, which is still current and under continuous development and revision.
        There is a reason your dictionary is entitled Oxford Dictionary of English, it is to distinguish it from its more illustrious and expansive parent. The ODE is a cheap, ready reference version of the real thing.

        • My “cheap” “school” dictionary cost £30 and has 2090 pages. I find it more than adequate and very much doubt that any school pupil would be strong enough to carry it to and from classes.

  1. Surely the beauty of language and the words we use is how they evolve and not just whether they appear in a dictionary? All words have to originate somewhere, maybe we should invent some more! The etymology of words can be fascinating – and teaches us a lot, but communication would undoubtably stall if everyone adhered only to the grammatical laws in place today without scope to evolve language for whatever the future holds…

  2. These comments are funny. “I’m almost positive, however, that every version of every valid word IS in the dictionary. ” That is laughable.

  3. I’m a bit baffled by this article, according to which the word “undoubtable” is stronger than the word “undoubted”. The former is defined as incapable of being doubted while the latter is defined as simply not doubted. In the example about the Beatles, then, wouldn’t it be more appropriate to express one’s own lack of doubt with the weaker and somehow more modest word “undoubtedly” than with the seemingly all-encompassing “undoubtably”, which to my mind would deny the possibility that someone else might disagree?

    I can see the other side of the coin but wonder if the article could be expanded to address the issue more fully. Thank you!

    • This was exactly my question after reading the article – it seemed that the author made a very worthy distinction between the two words, and then flipped them during the example given!

    • Undoubtedly means it literally isn’t doubted by anyone. Out of the two, it actually makes a stronger statement. Given that it could potentially be argued that people do doubt that the Beatles are the most influential band ever, undoubtedly doesn’t really fit. I would say, in this instance, undoubtably is more rhetorical or personal in it’s usage: ‘I’m personally unable to doubt that the Beatles …’, rather than literally saying it is universally impossible.


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