...f you ever reset your Keyboard Dictionary, it has the added benefit of preserving all of the words you've used it to designate. This method takes advantage of the fact that autocorrect accepts Contacts name entries as genuine words and won’t suggest that you change them.
Here's what you do:
Create a new contact, and type zzz as the initial letters in the Last field to keep it sorted at the bottom of the list, where it’s out of the way. Then type each of your special words, separated by spaces, into the First, Last, or Company field of the zzz contact.