Mutual friend is a xyz for the internet, or an internet dating site, when used to cover “how do you know…?” “oh, we met through a mutual friend“
These are friends on Facebook that you and another person have in common. That is, both of you know those people.
A person who is the friend of two people who may or may not know each other
Friends of two Facebook friends on a website like Facebook who are equally friends of both.
How to make mutual friends on Facebook
Sign into your Facebook account.
On the “Friends” option below your profile picture in the column on the left side of the page.
Click the “Manage Friend List” button at the top of the page.
Click the “+Create a List” button at the top of the page; a pop-up window will appear with a list of all your friends.
Type in “Mutual” in the “Enter a Name” field at the top of the Create a New List window, to name the friends list “Mutual.” Alternatively you can name the list with any other name you wish.
Scroll through the list of friends in the pop-up window and click on any friends you want to add to the “Mutual” list.
Click the “Create List” button at the bottom of the window to create the new list.