A sister-friend is much more than a best friend but unfortunately is not actually legitimately a sister. According to Urban Dictionary which has the most accurate definition of a sister-friend in my opinion, “Your bestesting friend. Whos been your friend for so long you might as well be sisters.

What is another word for close friend?

synonyms for close friendBobbsey twins.close friends.compadres.comrades.couple.friends.matching set.pair.More items

What is another word for best friends?

synonyms for best friendbosom buddy.close friend.companion.confidant.dear friend.pal.soul mate.