Pidgin Install Spell-checking support manually

Versions 2.7.0 and newer use the dictionaries available from the ​openoffice extension download site. You need to download the appropriate language extension file(s) (files are openoffice extensions *.oxt, which are just zip files that contain additional data). Once you have downloaded a dictionary extension file, you can rename it so it has a .zip extension and then extract the *.dicand *.aff files in it to <Pidgin Installation Directory>\spellcheck\share\enchant\myspell\ (create the directories if they don't exist already).
If Pidgin is running, it will need to be restarted for new dictionaries to be recognized.

Versions older than 2.7.0 use Aspell; you can download both the Aspell core and a dictionary from ​the win32 Aspell website.