When it comes to programming copy edits, there are lots of words that would otherwise be thrown out or replaced.

Hive uses a plugable design.

Should that be plugable or pluggable?

If the paragraph were talking about the Java language, I'd say pluggable, but a search for Hive and plugable has more hits than Hive and pluggable. That doesn't make them right.

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    Perhaps someone writing about Hive misspelt "pluggable" once (that is, they wrote "plugable"); and future authors discussing Hive just copied the error without applying too much thought. – user16269 Aug 7 '12 at 7:36
  • About the only thing I know of that’s plugable is Y2. – MetaEd Aug 7 '12 at 14:12
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    @DavidWallace That sort of thing happens a lot. Consider HTTP_REFERER for referrer. Or Perl writers who use ∗numification for nummification. – tchrist Aug 7 '12 at 16:50
  • Similar: "wrapable" or "wrappable" – sumelic Nov 21 '15 at 7:37

The "proper" use definitely seems to be pluggable, based on a dictionary entry and NGram:

enter image description here

Plugable does appear in some mainstream publications such as this one.

Interestingly, the earliest use seems to be a book from IBM written in 1942! Some kind of typewriter thing, it looks like?


The OED has only pluggable alone, dating from 1930. It does not attest plugable.

Based on the existing models of beggable and diggable, huggable and luggable, pluggable seems to be the more likely spelling by far.

The only counterexample the OED attests is the rare legable, meaning heritable (as opposed to something which is entailed).

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    Glad that we are of the same mind. I couldn't find legable with the meaning you indicate, whereas I found to lege (in Webster's Revised Unabridged Dictionary, published 1913) with the meaning of to allege or to assert, which obviously would become an adjective as "legable". The OALD does not list it. – Paola Aug 7 '12 at 13:15
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    ... which is intailed? I suspect that this is how plugable became a word ;) – coleopterist Aug 7 '12 at 14:05

I don't know what pluggable actually represents in programming, but it stands to reason that it should be spelt with double g. In fact, it is a monosyllabic verb just like "run", "stop", "cut" and so many others, ending in a consonant which needs to be doubled to preserve the correct pronunciation of the verb when used in the gerund or the past participle (obviously, if the verb is not irregular), for example. The suffix "-able" is the same as the suffixes "-ing" or "-ed" would be.

NOTE. As for the presence in the NGram of "plugable", I agree with David Wallace's comment above, that is that someone misspelt the term once in writing and others followed in the mistake. This adds to my mistrust towards the usage of NGrams versus reasoning.

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    You can find anything with Google, and often do. – tchrist Aug 7 '12 at 13:22

Pluggable has made it into some dictionaries. You won't find "plugable" in any. The preference for pluggable can also be confirmed via Google Ngrams:

enter image description here

However, as you have noted, plugable is certainly common if you go by Google's results. But, I don't believe that it's suitable for technical writing. It also does not appear to be the spelling of choice on 'oracle.com'; running a Google search restricted to Oracle's site returns 40,100 results for pluggable and only 2750 for plugable. The latter's hits are mostly restricted to forum and blog links, neither being what one might call bastions of reliability.


I am technical writer fighting a losing battle about this at my company. I have generated a bug for it. I have contacted the powers that be, who handled the sites through the company. They fix it in one place and it pops up in another. Now I find an entire site that spells it wrong: www.plugable.com. Sigh. I suppose this is how language changes. Still, I will use two "g's" until I see it in a dictionary.

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    Hello and welcome! This could make for a good answer with some editing: Make your answer to the question more explicit and support your subjective points with some evidence. See also how to answer questions. – Bradd Szonye May 9 '13 at 19:42

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