I used extrapolability in a Microsoft Word 2010 document and spell checker didn't recognized it. Being a non-native English speaker I wasn’t sure whether it's a real word.

Searching for it in Google I've found around 500 matches, some of them even in scientific texts.

Is extrapolability an existing English word?

  • 1
    Ngram shows its usage in scientific and economic texts since mid 50's. books.google.com/ngrams/…
    – user66974
    Aug 4, 2015 at 13:41
  • 2
    It is clearly a word. What else do you think it is? It most clearly is an existing word. And you've even supplied proof yourself.
    – RegDwigнt
    Aug 4, 2015 at 13:45
  • 4
    I think you have just answered your own question. Per Ngram, rare but in use since 1959. I for one immediately recognized what it would mean and why there might be a felt need for it, though I would probably try to find another way of expressing that meaning, on general principle. (The stylistic principle here is to use specific verbs to carry as much of the semantic load as possible, and not to let those verbs turn into abstract nouns instead.) Aug 4, 2015 at 13:46
  • 1
    The OED does have it (here, if you have a subscription). It has extrapolable as the head word, and then—inexplicably—both extrapolability and extrapolatable (but not extrapolatability) as derivations of that. Extrapolability is of course a derivation of extrapolable, but extrapolatable is not. And if extrapolatable is a word worthy of inclusion, so is extrapolatability, I’d think. Aug 5, 2015 at 11:26
  • 1
    One can hope not. That's a major candidate for mutation by syllable loss: Extrapability? Sep 4, 2015 at 14:21

1 Answer 1


'Extrapolability' is an existing English Word. My print copy of A Supplement to the Oxford English Dictionary (1972) does not, however list it. I am indebted to EL&U member Janus Bahs Jacquet who drew my attention to the presence of the word in the online version of the OED, as below:

extrapolable, a.
[f. extrapolate v. + -able; cf. interpolable a.]
Capable of being extrapolated. Also exˈtrapolatable a.
1940 A. J. Ayer Found. Empirical Knowl. iv. 224 Correlating the sense-datum with other sense-data, in such a way as to make its occurrence inferrible by the use of extrapolable laws. 1956 J. S. Bruner et al. Study of Thinking iii. 56 It makes a vast difference in behavior whether he is ‘set’ to find out the extrapolatable properties of the class of people who are influential. 1964 Amer. Philos. Q. I. 264/2 This merely makes the word ‘extrapolable’ bear the whole unanalyzed problem of induction. 1984 Oil & Gas Jrnl. 9 Apr. 88/2 This..law was..determined by experiments carried out under quite different conditions, thus guaranteeing its extrapolable nature on the Bousseus test loop. 1985 Ibid. 11 Feb. 84/1 There is no reason why extrapolatable data cannot be used.

Hence exˌtrapolaˈbility n., the quality or state of being extrapolable. 1968 Science 1 Mar. 935/1 Obviously the degree of extrapolability from evidence or crafts extant today must vary enormously from case to case.

A Google Ngram suggests that the word may have been in use prior to the first quoted example in the OED:

enter image description here

The earliest link from Google Books is dated 1930:

enter image description here

enter image description here

-from Contributions From The Physical Laboratory Of The University Of Michigan, Volume 6. A current day link to the 1930 paper is here: http://journals.aps.org/pr/abstract/10.1103/PhysRev.35.299

Other documents from the 1950's and 1960's containing this word can be found at this link: http://tinyurl.com/extrapolability

  • Thanks for the reference! could you please edit and add thoughts from the comment too? Answers are supposed to answer the question on their own, not just referring to comments. Nov 24, 2015 at 8:20
  • 1
    Thank you for the edit, and the prompt to take this a little further.
    – John Mack
    Nov 24, 2015 at 10:17
  • The hit and miss nature of Ngrams searches is apparent in comparing the search that I did and that done earlier by @Josh61. By which I intend no criticism of him, I'd simply set the parameters differently on a whim and was rather surprised by the result.
    – John Mack
    Nov 24, 2015 at 10:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.