My engineering dictionary is a little out of date, and I've been doing a lot of editing in civil engineering recently. So I asked my client which engineering dictionary they preferred, and they recommended this one. It is clearly laid out, has helpful diagrams and will be a useful guide to preferred spellings.
I don't know what the CAB stands for, but this is a searchable list of suitable words for use in the keywords section of your research paper. It seems quite nifty.
There is, of course, a website for Webster's dictionary and this is it.
Actually, the website is more than a dictionary; it also includes a thesaurus and an encylopaedia, and it has lots of fun extras, words of the day, lists, quizzes, and so on.
Today, I am looking at some German words, and I have found a useful site:
It finds examples of translations of different texts, which helps with context.
I picked this dictionary up as part of a special offer; it has quite a lot of useful information, easily laid out, although the edition I have is a little dated in some places. The longer items are sometimes a little quaint.
If you're editing a medical text in Word, you'll need to install a medical custom.dic, to avoid having a lot of correct words red-lined. These are easy to find on the Internet. I have installed one called MTH-MedSpelCheck.dic, and one called en_US_OpenMedSpel100.dic. (You do have to watch out for the US/UK variations.)
Instructions on installing a custom dictionary are also available at http://davidrothman.net/2010/02/21/how-to-add-a-free-medical-dictionary-to-word-20032007/
Today, I was editing an article on the subject of writing in plain English. This reminds me that the Plain English Campaign have a collection of guides to help in writing clearly.
For editing Science and Technology, you need a few good specialist dictionaries. Chambers Dictionary of Science and Technology was recommended when I first started, although it took me a whle to buy, as it often seems to be out of print. It is, however, very comprehensive, and has clear explanations.
This book is an intelligent guide to better writing. I consult it occasionally on points of usage, or to check the correct use of a tricky word.
Sometimes you forget the distinction between two words or would like to check up on a tricky word and need a longer explanation than you might find in the dictionary. This is a handy readable guide, and I find it most sensible.