dictionaryspellingtext;
I have accidentally learned 'formating'.
I've tried unlearning by right-click, and have removed the word from the /Library/Spelling and ~/Library/Spelling directories.
The word is still not underlined in red when I type it on various apps.
Is there any way to make sure the word is unlearned?
Pages recognises the word as incorrect, but not TextEdit or Google Chrome.
Yo ! Man, I got the best thing for you.
Just type some of your characters of word & press F5 & see the magic, It is what you want. Suppose your not getting the word rub some & get what you want.
Here is snap-shot of what you want. ( source of lots of shortcut keys )
Suppose, I am a user, I would do as follows.
simple & short just F5 does all for you, no need to press Cmd+: and then get correct one from list. It will give you list on the spot.
Warning: be careful about editing the system dictionary as it is easy to get an unusable dictionary. You also run the risk of having the updated dictionary over-written by subsequent OSX updates.
To edit the system level dictionaries, there is a helpful Q&A that tells you where to find the dictionaries: superuser.
In summary:
~/Library/Spelling/LocalDictionary
The System-wide equivalent, which is empty on my Mac, would be here:
/Library/Spelling/
Aside from this, you will find packaged dictionaries here:
/Library/Dictionaries/
~/Library/Dictionaries/
If it were me, I would just add the word to my personal dictionary. Although your question was how to edit the system dictionary, I note that on my system (10.8.2 Australian English) both your words are accepted.
But Microsoft Word 2011 (with Australian English) puts red lines under expresso and is happy with espresso.
It appears your example may be one of those where there is different usage in different parts of the world and in different software packages.
Best Answer
As a workaround: add the correction to your Keyboard prefs.
I know it's not the real solution you want, but perhaps helps in the mean time.