I have never used keyword synonyms until tonight, and the LR4 help isn't much help. It tells you how to add a synonym, but it doesn't tell you how to use a synonym.
I have a keyword called "Railroad Bridges". I edit the keyword to include the synonym RRBridge, and then save the new keyword definition.
Then, I was expecting to be able to type the synonym RRBridge into the Keywording Panel, and have it recognized and assign the keyword "Railroad Bridges" to this photo.
Didn't work. Nuh-uh. Created a brand new keyword RRBridge, distinct and different from the "Railroad Bridges" keyword. Which isn't what I wanted and isn't what I expected.
So, exactly how do you use keyword synonyms?