Learned Words
Spell checker engines rely on dictionaries to decide if a word is spelled correctly. To
      instruct the spell checker engine that an unknown word is actually correctly spelled, you need
      to add that word to a list of learned words. There are two ways to do this:
  - Invoke the contextual menu on an unknown word, then select Learn word.
- Click the Learn button from the Spelling
            dialog box that is invoked by using the  Check Spelling
          action on the toolbar. Check Spelling
          action on the toolbar.
Note: 
To delete items from the list of learned words, use the Delete learned
          words option in the  preferences page.
