In This Article
Best friend. A designation for one's closest non-romantic, non-family adult relationship. The term is in widespread use but resists strict definition; for most adults the working diagnostic is that a best friend is the person who would be called first in a crisis that did not require a partner or family member.
Where the term comes from
The English-language usage of best friend dates to at least the 16th century in the broader sense of closest friend, with the modern colloquial usage stabilizing through the 19th and 20th centuries. The term is interesting partly because it has survived essentially unchanged in everyday adult vocabulary even as relational vocabulary around it has multiplied; best friend remains the durable everyday word for the closest tier of friendship.
How it shows up in real life
A 41-year-old fields a 2 am text from a friend in crisis. She is not the friend's spouse and is not the friend's family. She is the person the friend called first. They have known each other for 19 years. They have lived in three cities each. The relationship has survived a marriage, a divorce, the death of a parent, a job loss, and one full year of estrangement. That sustained mutual investment across stress is the working definition of best friend.
Common misuses
Best friend is sometimes used too freely, applied to friends of recent vintage or to social-media adjacent relationships. The everyday meaning has the depth-of-investment and across-stress conditions implicit, even if not always stated. The other misuse is the inverse, applying the term so restrictively that it carries the weight of a permanent ranking; many adults have several relationships that meet the best-friend threshold, and the singular framing is a simplification.
