Remove Misspelled words and other Incorrect Entries from Firefox Dictionary Added by Mistake
When Firefox detects an incorrect spelling, it highlights that word with a dotted red underline – if you think the spelling is correct, you just right click and choose “Add to Dictionary“.
But if you make a mistake or accidentally add a wrong word to the dictionary, the only way to delete is by manually removing it from persdict.dat file.
you will see
delete the Misspelled word inside
note: ( Change mod to your own username )