I wanted to define some tags today (so many are left undefined when created) and chose to set the filter to "popular" and jump the the last page.
As it turns out, every single tag on the last page is a synonym of another tag and therefore cannot be edited. But you can't know that without clicking on each and every tag to see that it redirects to another tag. Even rolling the mouse over the tag name doesn't clearly reveal the tag to be a synonym — but it could confuse the user who compares the rollover popup's >0 questions with the original tag's 0 questions. A hint, but not a very good one, and still an inconvenient way to try and upgrade tags.
It would be tremendously helpful if synonyms were identified, especially in a way that also identified the parent. Something like this:
