What is the language override Constant for the Group "Admin" label?

When a member of an EasySocial group is made Admin they get a little green "Admin" label next to their name in the Members app. How can I override that label to "Leader"? I was thinking of using a language override but can't find the constant.

Also, is there a way for the site admin to post in Group page discussions without actually being a member of the group?