Change Core Slugs is a WordPress plugin (download) that allows you to set custom permalink slugs instead of default ones that are provided with WordPress core. This functionality is already available in WordPress, however it can be used by manually setting new configuration in the code. What this plugin does is that it provides friendly user interface where all site admins can change default slugs.
You can change:
authorbase in authors archives
searchbase in searches archives
pagebase in pagination pages of archives or in single posts
comments-pagebase in pagination pages of single posts comments
commentsbase in comments feeds
feedbase in feeds
When you change any slug, you will not get redirection from the pages that used old slug. Same goes if you again change any slug. If you want redirection, you must set it through server rules or with other plugins.
If you disable this plugin, old, default slugs will be restored and URLs with new slugs will stop working. The only way to keep new slugs is by manually setting them in the code.
NOTE: because of two bugs in WordPress core, in some cases setting custom slugs will not work properly. These cases are when `page` or `comments-page` include any non-ASCII character (ticket #41891), or when `feed` or `comments` bases are set (ticket #43274). Until these two bugs are fixed, you can use temporary plugin that includes fixes. You do not need that plugin if you do not use features that trigger bugs from above.
Change Core Slugs is released under the terms of GNU General Public License. It is completely free so if you find it useful you can give something back to author. Your help could be done by giving donation, sending pull request on GitHub, sending bugs and suggestions, promoting plugin in blogs, forums, social networks, and other websites.
Note: plugin author is not obliged to provide free support via this site, email, or official forum. If you ask for free support, please be aware that it might skipped.