While reading Richard II, I came across the word unpossible:

BUSHY: For us to levy power proportionable to the enemy is all unpossible.

This is the only use of unpossible in all of Shakespeare's plays. Impossible is used 44 times. I don't think the answer to "Why did Shakespeare only use unpossible once?" can be answered "Who knows? It's Shakespeare, anything goes." The use of unpossible is also in the 1597 quarto.

I also had difficulty finding online information about unpossible, other than that it is archaic and not used. I recently saw a game listed on Itunes and Googleplay called Unpossible.

When did the change to impossible happen? Why did it happen? There are many words in English that use the "un" prefix to say "not something:" Unjust, unfair, unloved, unhealthy, etc. When did unpossible stop being considered useable?

  • I think most questions about word choice asking why things are the way they are can only be answered "Because that's the way it is." While language itself may have some semblance of a rule structure, there's no such theory for word choice. – Matt Samuel Dec 8 '15 at 12:26
  • @MattSamuel I believe in this case it's not a matter of the capricious winds of change. – michael_timofeev Dec 8 '15 at 12:28
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    I say unpossible, but only for hypergeekery, on account of the Ralphism. – choster Dec 9 '15 at 16:39
  • I wonder whether Shakespeare chose 'unpossible' rather than 'impossible' in this case because he considered that "unpossible" fitted the dynamic of the iambic pentameter better. I personally find the transition from 'all' to 'un' slightly more comfortable than the transition from 'all' to 'in'. – BoldBen Sep 19 '20 at 18:57

Ngram shows a prevalent usage of impossible vs unpossible also in the past centuries. It appears that unpossible has always been a less common variant:


  • (Etymology) from Middle English unpossible, equivalent to un- ‎(“not”) +‎ possible.

  • (now rare, nonstandard) Impossible.

  • 1526, William Tyndale, New Testament, British Library 2000, p. 119:

    • And this is the. vj. moneth to her, which was called barren, for with god shall nothinge be unpossible.
  • 1621, Robert Burton, The Anatomy of Melancholy, New York Review of Books, 2001, p.280:
    • ’Tis a hard matter therefore to confine them, being they are so various and many, unpossible to apprehend all.


  • (Etymology) from Old French impossible, from Latin impossibilis, from in- ‎(“not”) + possibilis ‎(“possible”), from possum ‎(“to be able”) + suffix -ibilis ‎(“-able”).
  • Not possible; not able to be done or happen.

  • 1300 Cursor M. 14761 It es bot foli al þi talking, And als an inpossibile [Gött. impossible] thing.

  • 1340 Hampole Pr. Consc. 6281 Swa witty and myghty es he Þat na-thyng til hym impossibel may be.

Un-versus In- from Word Wide Words:

  • In general, words take un- when they are of English (Germanic) origin and in- if they come from Latin. (The forms im-, il-, and ir- are variations on in-.) Apart from that, there’s really no good guide to which one you should choose. You’re just going to have to stick to learning them by rote.
  • If it’s any consolation to you, the battle between in- and un- has been going on for centuries, with sometimes one form winning and sometimes the other, which suggests that the problem has been troubling English speakers for a very long time. As an example, for several centuries English had both inability and unability, but the latter disappeared in the eighteenth century for no very obvious reason.
  • Another is familiar from the American Declaration of Independence: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights ...”; these days, it’s inalienable (it should always have been, by the rule, since alien comes from the Latin alienus, of or belonging to another person or place).
  • Josh, I understand it is rare, but I think at one time it may have had equal footing with impossible but for some reason impossible died. Are there other instances of "un" words that died as well? I think the fact that the bard used it once when clearly it was a viable choice is quite telling...of what I don't know. Was there some kind of usage shift with Un and I'm words? – michael_timofeev Dec 8 '15 at 12:37
  • @michael_timofeev - the prefix un- is less used or archaic vs in/im- , another example is impolite vs unpolite. english.stackexchange.com/questions/233724/… – user66974 Dec 8 '15 at 12:54
  • It's interesting reading the comments for that question..."educated people don't use it." I suppose the more Dickens and Shakespeare one has read the more one would use those "uneducated" words. – michael_timofeev Dec 8 '15 at 13:11
  • I wonder if the reason "im" seems to be winning is because it's easier to say "impolite" or "impossible." The P is ready to be pronounced when following an M whereas with N it's "inconvenient." – michael_timofeev Dec 8 '15 at 13:12
  • Good edit about the Declaration of Independence. Thanks. – michael_timofeev Dec 8 '15 at 13:15

Unpossible is not entirely verboten.

OED records it as "very common c1400–1660", but has citations from 1382 to the twentieth century and culminates with

2008 L. D. Brodsky Dine-rite 28 It's goddamn-to-hell next to unpossible To serve up taste-temptin' eats.

which is colloquial, but indicates that the word is used in some circumstances. Those circumstances would appear to be quoting a character's speech. ODO notes the word as "Now chiefly informal and regional".

Impossible is easily formed from the Latin impossibilis, and OED has citations from 1340.

It appears that the two words lived side-by-side for three hundred years before the Latinate impossible definitely gained the upper hand in the seventeenth century, when use of Latinate words became more popular. Because Google's Ngrams show relative frequency, and only go back to 1500 anyway (and there isn't an enormous amount of source material from that period), evidence from statistics may not be entirely reliable.

  • What I find interesting is that Shakespeare only used it once when clearly he could have used it more often...were there other un words that died? – michael_timofeev Dec 8 '15 at 12:42
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    @michael_timofeev: I wouldn't read too much into the "one use by Shakespeare" business. Because there are so few really old copies of his works (none original, I think) we probably can't say for certain whether he actually used that version once, several times, or never. Plus it's worth noting that a Google Books search finds only 302 instances of your version of the quote, compared to 662 with impossible. Shakespeare himself wasn't consistent (he never spelled his own name the same way twice, in half-a-dozen surviving examples), but it might just have been a copy "error" anyway. – FumbleFingers Dec 8 '15 at 13:34
  • @FumbleFingers So what about the quarto from 1597 that I linked to... – michael_timofeev Dec 8 '15 at 13:36
  • @FumbleFingers The First folio uses "impossible." The 1598 quarto uses "unpossible" Also, the TV program The Crown uses "unpossible." – michael_timofeev Dec 8 '15 at 14:01
  • @michael_timofeev: I certainly wouldn't set any store by the usage promoted by a TV program - they're quite capable of making their choice simply on the basis of what gives the best "Olde Worlde" flavour to the text. Whatever - we know unpossible was used far more in the past in other contexts, but has massively declined over the past century. – FumbleFingers Dec 8 '15 at 14:35

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