I understand tags can have synonyms, for example [rpg] can be a synonym of [role-playing-games]. How can I suggest new synonyms to existing tags?
Visit that tag's page and click on the info tab. If your suggestion has already been made, upvote it.
You can also see a list of pending and active tag synonyms.
Once a suggestion reaches a score of 3, it is automatically accepted.
As of August 2, 2010, users require 1000 reputation in order to suggest tag synonyms.