My question is referring to the prefix iso- and its meaning in the word isolate. My question is, if the prefix means equal, how does that make sense in the word isolate?

  • 5
    30 seconds on Google got me this: back-formation from isolated set apart, from French isolé, from Italian isolato, from isola island, from Latin insula
    – Hot Licks
    Commented Mar 2, 2015 at 2:53
  • 2
    Strictly speaking, it should have been insulated, not isolated. The root has undergone a distortion along the way. Insulated is also used, in a closely related meaning.
    – Kris
    Commented Mar 2, 2015 at 5:40

1 Answer 1


The etymology of isolate is not the same as the prefix 'iso'.

isolated (adj.) 1763, from French isolé "isolated" (17c.) + English -ated (see -ate (2)). The French word is from Italian isolato, from Latin insulatus "made into an island," from insula "island." The French word was used at first in English (isole, also isole'd, c.1750), then after isolate became an English word, isolated became its past participle.

iso- word-forming element meaning "equal, similar, identical; isometric," from comb. form of Greek isos "equal to, the same as" (as in isometor "like one's mother"). Used properly only with words of Greek origin; the Latin equivalent is equi- (see equi-).

Source: http://www.etymonline.com

  • 3
    If it was insula in It., why and when did it produce isolato?
    – Kris
    Commented Mar 2, 2015 at 5:42
  • @Frank Your request was perfectly reasonable, the site wouldn't be what it is without sources.
    – Minnow
    Commented Mar 2, 2015 at 17:37
  • @Kris Was your comment ever answered? Or was it a witticism that I missed?
    – user50720
    Commented Mar 17, 2015 at 23:09
  • @LawArea51Proposal-Commit The endorsement shows that it, after all, makes sense. Even I could find a satisfactory answer so far. :)
    – Kris
    Commented Mar 18, 2015 at 6:45
  • @Kris: Thanks for your comment. To clarify, do you mean that your comment of Mar 2 was answered in the Answer above? I had interpreted it as postdating the answer.
    – user50720
    Commented Mar 18, 2015 at 15:52

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