You can use SCOWL,  Spell Checker Oriented Words Lists,  in order to determine the frequency of the spelling of a word, and check whether or not a word is in the open source spell checking program, Aspell, made available by GNU.

If you enter a word on 

http://app.aspell.net/lookup

.. . you'll get search results like this:

Note that an open source word list like this one (which can be downloaded) can be use by hackers in brute force attacks so it may be  a good idea to avoid using words found in it.