Which form is correct (or more correct): reimplement or re-implement?

And to extend the question a little bit, are there any rules concerning both, e.g. re-scan or rescan, re-evaluation or reevaluation?


The primary question is if both versions are correct (or which one is more correct from the English grammar's point of view). I know that both are in use, it's easy to do Google search for example to find out that "reimplement" is even more widely used than "re-implement". But in that case, why LibreOffice marks "reimplement" as incorrect? Is the construction informal? Incorrect? Because clearly is quite popular.

The second part of the question is somehow answered by the other question pointed to in the comment, e.g. I may use the hyphen if that makes the meaning more clear (which doesn't apply to this case IMHO).

  • Thanks Chris for correction. It's a pity I can't vote up for corrections :)
    – Greg
    Commented Feb 26, 2016 at 16:44
  • It doesn't look like a duplicate of that question because I am not asking if I should use "re implement" (as two words) or re-implement.
    – Greg
    Commented Feb 26, 2016 at 17:09
  • The issue is this. Will reimplement cause any confusion to readers? If you don't think so, you can use reimplement. The answer to the previous question clearly states so.
    – user140086
    Commented Feb 26, 2016 at 17:14
  • Are you saying both are grammatically correct and I can use whichever I prefer?
    – Greg
    Commented Feb 26, 2016 at 17:29
  • 1
    I think the answer is given by "For the most part, compound words that are created by adding a prefix are not hyphenated. For example, there are the words anteroom, extraordinary and coordinate. Some exceptions to this rule are: compounds which need hyphens to avoid confusion, compounds in which a vowel would be repeated, compounds consisting of more than one word, compounds that would be difficult to read without a hyphen"
    – herisson
    Commented Feb 28, 2016 at 3:06

2 Answers 2


Thanks for all the answers, but I found what I was looking for in the Hyphens with the Prefix re article:

Rule: Use the hyphen with the prefix re only when re means again AND omitting the hyphen would cause confusion with another word.

The article then provides some examples (which I am not copying here).

In other words, "reimplement" is the grammatically correct version because there is no other meaning associated with the word "reimplement" and therefore the use of hyphen is not necessary.

This somehow confirms why there is more results in favor of "reimplement" than "re-implement" on Google - the later (less correct, if not incorrect) form is probably a result of the confusion around the usage of hyphen with re.

This is of course based on the assumption that the article is trustful.

Edit: Cater for re-examine

The same page mentions an additional Rule:

Rule 3. For clarity, many writers hyphenate prefixes ending in a vowel when the root word begins with the same letter.

Example: ultra-ambitious semi-invalid re-elect


  • Don't forget Oxford Online Dictionary lists the verb re-examine with a hyphen even though reexamine is not likely to cause any confusion. Again, there is no rule except you have to use the hyphen if it could cause a confusion. And it depends on your style and preference.
    – user140086
    Commented Feb 26, 2016 at 17:54
  • Yeah, they give the rule that I mentioned in my edit. According to them it's a special case because the root of the word starts with 'e'.
    – Greg
    Commented Feb 26, 2016 at 18:08
  • Yes, I think that is close to the rule. +1) Well done.
    – user140086
    Commented Feb 26, 2016 at 18:11

As a native Dutch speaker, this is one of those things that always require me to think before I type because I never seem to remember the exact rules.

This website deals specifically with the hyphenation of pre-fixes.

I've only just found it myself but it appears to answer all your questions in a good way with lots of examples.

An excerpt:

Guiding Principles for Hyphens with Prefixes If it's not a spelling mistake to avoid the hyphen and you can bear how the words looks without it, then avoid the hyphen.

Often, it's your choice whether to use a hyphen. Lots of prefixed words can be written with or without a hyphen. The underlying guideline is:

Try to avoid a hyphen with a prefix. However, if you feel the word looks too >unwieldy without a hyphen or if your spellchecker highlights it as wrong, then add a hyphen.

  • The answer to the duplicate question I posted in the comment says compounds which need hyphens to avoid confusion: un-ionized (as distinguished from unionized), co-op. If you say some prefixes need hyphens, it sounds like it depends on the prefix. The problem is un and co are missing in the examples. Also, you need to capitalize dutch.
    – user140086
    Commented Feb 26, 2016 at 16:53
  • I think that comment and my post crossed eachother, my apologies. You are correct of course in there being more pre-fixes, and I will update my answer accordingly. /bow
    – Terah
    Commented Feb 26, 2016 at 17:07
  • One more tip if I may. Please use the search to see if there is any duplicate of the question asked. We have close to 67,000 questions in our database. Many questions are duplicates. The policy is if you find a duplicate and if you have a better answer than the existing ones, you post an answer to the previous question, not to a new one. That means you should not post an answer here if you find the question is duplicate. You will understand it more as time goes by.
    – user140086
    Commented Feb 26, 2016 at 17:11
  • I did search for a similar question but nothing came up. I am not interested on rules when a hyphen should be used or not. I am asking which version is correct. According to Google search there are 379,000 results for "reimplement" and 264,000 results for "re-implement". Of course it's not indicative, but I am curious why my word editor marks "reimplement" as incorrect if it's more widely used than "re-implement"
    – Greg
    Commented Feb 26, 2016 at 17:14
  • 1
    @Amiramix You can never trust MS Word or any other program for typographical errors or grammatical errors. There is virtually no unified rule governing punctuation. It largely depends on your style and preference and which manual you or your editor use. I don't see any problem using both of them, but I don't think reimplement will cause any confusion to readers.
    – user140086
    Commented Feb 26, 2016 at 17:17

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