If adding is what you just need then this answer might work for you. If you want to install a new dictionary, follow the link in the comment. With your terminal, cd to the directory of your TeXMaker dictionary. If you don't know where, in TeXMaker click
Options > Configure TeXMaker > Editor
You can see the directory of the dictionary in the option Spelling dictionary. In Ubuntu, once you are in the directory, type
sudo gedit en_GB.dic
and put the word you want to add in there.
In Windows, just go to the directory and double click on the file or open with Notepad. Then write the word you want to add.
You might also want to save the customized file in another folder and have your Spelling dictionary option point to the custom file.
I had the same problem but the
.dicfiles that I used didn't work.
To solve this error you need to install the spell-checker
sudo apt-get install myspell-de-de myspell-en-usor use
sudo apt-get install myspell-*
Then find the dictionary:
There were two directories that contained dictionary files in my computer;
/usr/share/myspell/. Only one of the "myspell" dictionaries worked, while all the "hunspell" dictionaries worked (so far) .
.dicfile from "myspell" doesn’t work without a corresponding
.afffile that you want and enter its path into texmaker at
options --> configure texmaker --> editor --> spelling dictionarythen click ok.
Right click on your "code" and click on
check spellingto make sure it's working.