Chemistry Dictionary for Word Processors V3.0


Download the Chemistry Dictionary(V3.0) here


1/13/12: Welcome J. Chem. Educ. readers! After you download the dictionary, feel free to browse to the front page and have a look around. You may also be interested in our Reagent Table Calculator Widgets. 🙂

1/19/11: Reader Catie has forwarded a biology/medical dictionary that is also free and fully compatible with the chemistry dictionary or other custom dictionaries.  Read about it and download it here.

Original December 17, 2008, post follows:

As anyone who’s written a paper for chemistry class or journal publication knows, spelling “errors” quickly become so numerous that you just ignore them. They’re not really errors, of course, just technical words that Microsoft’s standard dictionary doesn’t include. This is problematic for at least two reasons. One, I tend to gloss over the many, many squiggly red lines and therefore not notice actual spelling errors that have been made. Two, the standard spell checker cannot differentiate between correctly-spelled technical words and misspelled technical words. Thus, all technical words come back as misspelled whether or not they actually are misspelled.

Around this time last year (end of 2007), I was looking for a solution to this problem. I wanted to download a free “custom dictionary” to upload to my word processor to recognize all the words that were correctly spelled, but not recognized by the standard dictionary. Surprisingly, I couldn’t find one. I found several scientific spell check programs, but they are all for-pay versions. I wasn’t interested.

So I set out to create my own chemistry dictionary. I finished it up at the beginning of February (2008), and it was hosted at Sciencebase with thanks to David Bradley (read the post regarding the original release). The dictionary was relatively small, containing some 18,000 words. But it helped a lot.

Through David, I was introduced to Antony Williams from I met with him one afternoon in February, and he agreed to release his database of 1.3 million identifiers for me to integrate into the next upgrade. (Update: read Tony’s writeup)

It took me a while, but the upgrade is complete and ready for release.  Click here to download the zipped chemistry dictionary file (V3.0).  The 1.3 million identifiers were distilled down to around 102,000 additional words for the dictionary file (read more on that process here).  This upgrade bumps the dictionary from 18,000 words to ~104,000 words.

Administrivia: The dictionary is licensed under the Creative Commons Attribution 3.0 License.  The dictionary is compatible for Microsoft Office (Windows or Mac), and  Open Office (Windows or Linux).  The install file includes instructions for upgrading old versions and installing it for the first time.  The dictionary should be useful for all chemists.  However, I am an organic chemist.  Thus, the dictionary was created from an organic chemist’s mindset.  It will probably be most useful for organic chemists.

Now, I can’t guarantee that the dictionary is perfect. If you have comments, questions, or suggestions, you can leave them in the comments or email me at chemdictionary – at – gmail – dot – com. If you notice a word not in the dictionary that you’d like to see added, you can enter below it in the form that Mitch made for me. (Thanks, Mitch) I’ll review it and consider it for the next upgrade.




  • Several people have emailed me saying they are experiencing some problems integrating the dictionary file with Microsoft Word on a Mac.  Here is a useful workaround:Open the dictionary file through Microsoft Word (open Word, then goto Open File and change the file type to All Files).  With the dictionary file open, select “Save As.”  One of the “File Type” options to which the file can be saved is a custom dictionary file.  Save the document as a dictionary file with a novel file name.  Then follow the instructions in the install file to add on this new dictionary file.
  • Two people have independently (and most kindly) formatted the dictionary file for integration into iWork for Macs (OS X only, I believe).  I don’t have a Mac, so I have no idea what that is.  But if two people went out of their way to reformat the dictionary file for it and sent the file to me unsolicited, then it must be good.  Here it is (zip file) (Update: The iWork file has been incorporated in to the standard download).  This does not replace the dictionary file for Microsoft Word on a Mac.  You will need to install both files if you use Microsoft Word and iWork.  If you have already created a custom dictionary for iWork, you will need to append this dictionary file to the end of your current custom dictionary.
  • Read the article I wrote for the inaugural issue of the ChemSpider Journal of Chemistry.




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  1. awesome! My thesis and I thank you very, very much.

  2. Great idea! I’ll try it. I hope it doesn’t overwrite my own custom dictionary…

    • It wont…

      A bit of Microsoft trivia: If a user has previously added words to their dictionary, the added term is not appended to the user’s default English dictionary. Rather, Word creates a “custom” dictionary on your behalf, and conveniently names it CUSTOM.dic. Search your computer (Start Menu–>Search) for ‘custom.dic’ But before you begin the search, click on ‘More Advanced Options’ to make sure ‘Search Hidden Files and Folders’ is checked. That should point you to the location of your custom dictionary file.

      Adding this dictionary will just add a second custom dictionary to your list. Word should check its default dictionary, then the default custom dictionary, then the chemistry custom dictionary.

      PS. In the ‘add a dictionary’ mode, you should also be able to designate the custom dictionary to which subsequently added terms are placed.

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  4. Brad VanMiddlesworth says:

    I hope random dirtbags don’t come along and flood your new_words.txt with naughties.

    Thanks for taking this project on. I’m always a huge fan when someone decides to “do it right, do it yourself.”


    • I hope random dirtbags don’t come along and flood your new_words.txt with naughties.

      Ha. Me too. Fortunately, the words don’t go directly into the downloadable dictionary. They sit in new_words limbo until I decide to add them to the next upgrade.

  5. You rock! I’ve been wanting an add-on like this for YEARS!

  6. Woot! Installed and working. 🙂

  7. Cool. I’ve accumulated my own chemistry dictionary by adding the words that I’ve typed over the years, but it is nowhere near this extensive. Thanks!

  8. OpenOffice is much better then Microsoft word.
    Well, maybe not much better. Better in many ways. Plus legally free! I much prefer it.

    Convert it to an OpenOffice dictionary. It is really easy. I do not want to steal your thunder other wise I would do it.

    Though, my normal OpenOffice dictionary is already pretty good, as it is just one click to add a word to the dictionary!

    OpenOffice for the win!

    • Brad VanMiddlesworth says:

      The one downside I’ve found in Open Office is that there isn’t a way to put a regression equation directly on a graph as there is in excel.

      Mind you, there are better graphing/regression programs than excel, I know. Just a pet peeve of mine about Open Office.


      • That was fixed in version 2.5, version 3.0 has been out for months now. Yes it was always annoying, and made it hard to recommend for GenChem students. But has been fixed for a while.
        Not that it was hard to do it manually. The thing about OpenOffice I like now with the trendline equations, is it uses f(x) instead of the stupid y=, I come from old school math and hate y= and when I was using Excel would have to do it manually, regardless.

        • Brad VanMiddlesworth says:

          Ah, I didn’t know it was fixed. I tried it about a year ago and stopped suggesting it to students based entirely on that.

          Or rather, a more correct statement, when I suggested it I mentioned that it didn’t print the equations and that it wasn’t trivial (to a non-user) to find the slope and intercept. I generally showed them once and then left them to their devices, with mixed results depending on the student.

          I’ll have to check out 3.0 now, of course this will be effectively null to me as I’m done teaching, hopefully for my career.

    • It has openoffice instructions in the file!

      • Yes, that is the old method for OpenOffice dictionaries (and will work with the new). They are now in the new version (3.0+) treated as extensions, and are really easy to make. So you can just click a web-link and it installs the dictionary. It will also get it listed on OpenOffice’s website for extensions. Which is what I meant by stealing his thunder, as he should get the credit for it by being the extension/dictionary author on the website.

        • They are now in the new version (3.0+) treated as extensions, and are really easy to make. So you can just click a web-link and it installs the dictionary.

          Even for dictionary files with >100K words? That was the major problem I had when I was putting together the first version of the dictionary.

          Back then, custom dictionaries could only hold 2,000 words. That meant to add the chemistry dictionary as a custom dictionary would have required 9 different custom dictionaries… and that’s when it was only 18,000 words.

          That arbitrary limitation has since been expanded to 30,000 words… still not big enough for this upgrade ( I don’t know anything about the dictionary extension. Will the size of this dictionary be a problem?

          Can you point me to a site so I can learn more about it and try to upload the dictionary as an extension?

          • I had not clue about the Dictionary size limit. I see from your bug link you even commented on it earlier this year, too!

            It really seems like an odd limit though, as the English language has hundreds of thousands of words in it. Wonder how that is handled.

          • I’m not really sure what I need here. I downloaded the sample description.xml file and modified it. I think I did that right, but since I’m not fluent in OOo, I wasn’t sure exactly what went where. I made text files for the license text, release notes, and description.

            Is that it? Do I just package all that with the dictionary file in an *.oxt file? Then what?

  9. I am seeing this link on other blog sites now 🙂

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  13. How do I make it one of my custom dictionaries in TeXnicCenter?

    • Allow me to be answering my own question. The custom dictionary is too big to use in TeXnicCenter, but you can replace US_en.dic because it’s in the OpenOffice format. In the meantime, you can still add custom words to a custom.dic file for words that aren’t in the dictionary like triazoline.

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  15. You should get mitch to rig you a digg-like thing for the new words, to help you weed the bad from the good ones. People can come and vote the good words to the top, and comment, maybe there is a misspelling or something…

    Kind of a lot for something so small, but it would be so many level of badass, lol.

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  17. I just hope somebody with the skills/know-how/time required will do the same for molecular biology…

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  20. I was having issues getting it to work on my mac at the lab, so I just opened it up, copied it, and pasted it into the existing dictionary file.

  21. This is really cool. Thanks.

    Have you figured out how to load the dictionary with Open Office 3? The directions included in the zip file don’t seem to apply. The folder to unpack in does not exist, and when I make it OO doesn’t seem to find the dictionary.

    • I’m working on making it an extension. I’m just not that familiar with OO.o and how to code the various parts. When it’s done, you’ll see an update here.

      • Please let me know when you’ve got a file and way to install your excellent dictionary in Open Office 3.0. Thanks.

        • as a workaround for right now, if you can find the folder where en_US is currently located, you should be able to overwrite that file with the one in the zip file.

          Will update when I have more info about the extension.

  22. I am both a chemist and an editor who uses a Mac. For most purposes I use “Word” for Mac but I also use iWork’s word-processing program. When I downloaded what is purportedly the “iWork” version appearing in the 1/209 Update #2, the download was in the form of a Unix executable file and seems not to be usable on my iMac. Am I missing something or misunderstanding how this file is to be handled?

  23. I have another question about installing the dictionary on an iMac in addition to what I posted above on 2009-02-23 @13:23:26. I tried following the installation directions for Word for the Mac. and have run into a problem. The questions are this: (1) In what format is “ChemDictMac” to be saved to the Microsoft folder in the Preferences folder of the Library folder? (2) I inserted the file in a Word format and found that when I try to use it by choosing it I get a “XXX Dictionary is not available for use” message”. Why?

    • Word format is no good. You need to open it in Microsoft Word and resave it as a custom dictionary file. see update 1 above.

  24. You should add the amino acids for us Biochemists!

    Great Job though!

  25. You are a god! No more red squiggles everywhere!

  26. Thank you very much for the great resource!

  27. I’m still confused on how to add this dictionary to OOo 3.1… Any step-by-step help or how-to-links? Please????

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  29. Thank you so much for this dictionary! It makes my writing of chemistry articles much easier!

  30. hello, i downloaded it , but could not get it installed on Ubuntu Lucid with ooo 3.2.

    Could u please give some help?

  31. Pingback: Chemistry-dictionary integration to word processor or OS « வழிப்போக்கன்-Mac OSX

  32. Quoting dofine:

    hello, i downloaded it , but could not get it installed on Ubuntu Lucid with ooo 3.2.

    Could u please give some help?

    It’s apparently not easy, but possible. See here:

  33. i couldn’t install the dictionary.
    i use microsoft word 2004 for mac version 11.5.6 (090722).
    i think the dictionary is not able to apply to japanese microsoft word.
    if someone have any solution for this, please tell me.

  34. Thank you for the amazing work! Trying to share it with more friends~

  35. When I download the zip file there is nothing in it. Error message States cannot open file; Does not appear to be a valid archive. I have tried downloading it 3x with the same message when I attempt to open it.I have a Dell.
    Thank you

  36. Thank you for your note, KeenRocha. Sorry for your frustration. I cannot duplicate your error on my computer. What operating system are you using on your dell?

  37. Using Windows XP
    azmanam @ Jan 28, 2011 – 01:01:59:
    Thank you for your note, KeenRocha. Sorry for your frustration. I cannot duplicate your error on my computer. What operating system are you using on your dell

  38. Please continue to try your download, as I still cannot reproduce your error. When you download the .zip file, make sure you save it to your desktop so you can find it easily. If you continue to have issues, you may email me at chemdictionary at
    gmail dot com.

  39. I not sure if i have done it correctly but when I dowloaded, all i got is .txt files and there’s no .exe file.

  40. @Sami: That’s correct. There’s no .exe file. Open the install.txt file and follow the instructions to add the dictionary to your word processor of choice.

  41. i’m not sure if its from installing this dictionary, but now the top of my word 2007 is all white and strange looking!

  42. sorry never mind it didn’t have anything to do with the dictionary! and this is awesome by the way, excellent job!

  43. Great work. This will complement my ever growing list of biosci-related words … organisms, enzymes, acronyms, etc.

    Maybe you can recommend a list of common organic chemicals with name, CAS, MP, BP, MW and whatever that I can use instead of Merck Handbook, and extend with inventory, hazcon and supplier notes. I’ve built up something like this in Excel over the years, but it is woefully inadequate.

  44. Hi, you are doing a great job!!! It realy titanic job to create and support the dictionary by yourself. May I help you providing this link to on-line medical dictionary as it terms are closely related to Chemistry. Oh, and it has a medical spell checker as well.

  45. Joshua McAteer says:

    Thankyou ever-so much, for years I have had to flick between the correct spelling on wikipedia, or else and text book, and an essay. And had to try and ignore the hundreds of red caterpillars that sit under tryptophan. You are a credit to society and the wider internet community. 🙂

  46. Many thanks for your contribution to scientific writing!!

    However, I encountered a problem… I successfully added the dictionary to MS Word (2003), but only words beginning with the letters “a” ad “b” appear; the remaining words in the dictionary appear in Wingdings font.

  47. It works in LibreOffice too. Maybe you should mention it 😉

  48. This is so awesome. Very much appreciated. FYI your help section for using a mac on 1/22/09 left a lot to be lacking at least for microsoft office 11 for macs but I found these directions which helped me a bunch:

    1. Make sure that a document is open. If no document is open, the next step won’t work.
    2. On the Word menu, click Preferences.
    3. Under Authoring and Proofing Tools, click Spelling and Grammar.
    4. Under Spelling, click Dictionaries.
    5. Click Add, and then locate and double-click the custom dictionary that you want to import. If the custom dictionary doesn’t have a file name extension of .dic, on the Enable pop-up menu, click All Files.

    Thanks again!

  49. Thank you so much, this is the best dictionary i have ever seen. This will say me so much time on everything i type. THANK YOU!!!

  50. Whoa, this is amazing!!!

    Thank-you for this dictionary! It’s going to be a blast using it in my undergraduate chemistry studies. It’s always been a pain for my spellchecker underlining red in all my sentences.

  51. Can not download the chemical dictionary, please help!

  52. Very impressive. Thank you!

  53. Those red squiggly lines have been haunting me till now! This is truly a Godsend!! Thanks a lot 😀

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  56. George Dionne says:

    awesome, thank for you sharing

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  58. Good idea and helpful post…

  59. Ꭲhis knire only has four tools available to users.

  60. This is such a great article!

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