Where does the adjective form extensible come from and does it connote anything different than extendible? What's the difference, if any, between the two?

  • 14
    ...additionally, is there a difference between extendible and extendable?
    – SF.
    Commented Nov 7, 2012 at 8:09
  • 2
    Related post on Programmers.SE Commented Nov 7, 2012 at 8:33
  • 3
    -1 for not showing any research. Commented Nov 7, 2012 at 8:35
  • 1
    Historical comparison: books.google.com/ngrams/…
    – Myer
    Commented Jul 7, 2016 at 8:29
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    @MattE.Эллен ... I'm pretty sure you understood the question just as well with or without research...
    – user189910
    Commented Nov 8, 2017 at 14:27

6 Answers 6


It appears that I probably draw a finer distinction here than others may, but the good thing is that for those that say the two are interchangeable, my usage will seem unremarkable, and for those that care, my usage will seem consistent.

I use extendable in cases where it means the opposite of retractable. In other words, a telescoping wand is extendable, the legs of my camera tripod are extendable.

I use extensible when I mean that the functionality of something may be increased or enhanced by the addition of an extension- an add-on module or component. My web browser is extensible because I can add an Adobe Flash extension which allows me to view flash content. I think it would sound a bit odd to talk about my web-browser being extendable.

  • 29
    So, if you can buy special attachments for your tripod that will allow you to mount different equipment upon it, then I suppose you'd have an extensible, extendable tripod.
    – J.R.
    Commented Nov 7, 2012 at 8:43
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    You may be right. I like your nuance.
    – tchrist
    Commented Nov 7, 2012 at 13:41
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    This distinction reminds of farther vs. further.
    – 0 _
    Commented Sep 24, 2017 at 5:39
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    @0xc0de - Well it was 2012.... :-)
    – Jim
    Commented Nov 21, 2017 at 13:51
  • 4
    I like this: extendable means it can be made bigger by itself; extensible means it can be made bigger by adding something (an extension).
    – CSJ
    Commented Nov 28, 2019 at 14:16

There are lots and lots of these. They usually came to us that way straight from Latin, and seldom mean anything different from each other. One may be more rare than another, though.

  • comprehendible, comprehensible
  • corrodable, corrodible, corrosible
  • defendable, defensible
  • deridable, derisible
  • dividable, divisible
  • evadable, evasible
  • expandable, expansible
  • explodable, explosible
  • extendible, extensible
  • inevadible, inevasible
  • invadable, invasible
  • offendable, offensible
  • persuadable, persuasible
  • protrudable, protrusible
  • reprehendable, reprehensible
  • rescindable, rescindible
  • revisable, revisible
  • subdividable, subdivisible
  • suspendible, suspensible
  • undefendable, undefensible
  • undividable, undivisible
  • 12
    hopefully no one mistakenly confuses sensible and sendable :)
    – Andy
    Commented Jan 10, 2017 at 1:38
  • 2
    if it is not sensible it is not sendable
    – Andrew
    Commented Jan 19, 2017 at 1:54
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    When spelling in English couldn't get any easier
    – user189910
    Commented Nov 8, 2017 at 14:21

The Oxford Dictionary of American Usage and Style (2000) says:

Other variant adjectives, though, are merely duplicative. Typical examples are extendable, extendible, and extensible. The first of these is now prevalent in AmE (though labeled obsolete in the OED). Extensible was, through the mid-20th century, the most common form, but today it trails extendable by a substantial margin, while extendible continues to appear infrequently. Writers and editors ought to settle on the most firmly established form--extendable, which is as well formed as the variants--and trouble their minds with weightier matters.



The Oxford Dictionary for Writers & Editors says:

extendible, not -able, but in general use extensible not -able


In WordReference site, its given that extensible means capable of being extended.

extend/ɪkˈstend/ verb

1 make larger or longer in space or time.
• occupy a specified area or continue for a specified distance.

2 hold (something) out towards someone.
• offer or make available.

3 (extend to) be applicable to.

4 strain or exert to the utmost.

– derivatives
extendability noun,
extendable adjective,
extendibility noun,
extendible adjective,
extensibility noun,
extensible adjective.

Also want to add some info got from another useful source,

Extensible seems to me to indicate stretchability whereas extendable suggests an opening out or lengthening. An elastic band is extensible, i.e.: it can be stretched, whereas my lunch hour is extendable, i.e.: it can be added to, but an hour is an hour and cannot be stretched. There is also extensile which seems to mean the same as extensible.

  • 1
    It would be good if you could cite the source from which you quote.
    – Jim
    Commented Nov 7, 2012 at 7:15

I use the terms as Jim does in the context of Computer Science. In a computer program, if I add subroutines or blocks it is extendable - I can add more blocks. If the program is extensible, the individual blocks may be made more complex by modification, usually adding flexibility.

  • 1
    "made more complex by modification, usually adding flexibility". You might make them more complex, or you might simplify them. A technique used is to add flexibility, but flexibility can be a characteristic of extensible code. In short - I think your answer can be improved
    – Crowie
    Commented Mar 5, 2014 at 11:15

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