best friend

American  

[best frend] / ˈbɛst ˈfrɛnd /

noun

1. a person’s closest or most cherished friend.

   Sheila has been my best friend since we were seven.

   Synonyms:

   bosom friend, bosom buddy, bff, bf, bestie

2. something that a person particularly depends on or has a special affection for.

   A purple, stuffed armadillo was my best friend and companion through my whole childhood.

3. something considered or suggested to be particularly useful or valuable.

   When it comes to saving for retirement, compound interest is your new best friend.

   Your local piano tuner could be your best friend when buying a piano.

---

Etymology

Origin of best friend

First recorded before 1000

Example Sentences

The first time Leigh Digons saw the Backstreet Boys, she was 15, with her mom and best friend.

From The Wall Street Journal • May 6, 2026

It would be like a best friend who’s always there for you and endlessly helpful.

From The Wall Street Journal • May 3, 2026

"My mother-in-law and best friend died from heart complications," he said.

From BBC • May 3, 2026

Wales captain Jac Morgan has been praised for leading from the front when playing for Ospreys the week after the death of his cousin and "best friend" Harri.

From BBC • Apr. 21, 2026

His fellow merchants had abandoned him, and his best friend had paid a fortune to hire the murder god of an accidental religion—Cid, who had been my first love.

From "The Many Assassinations of Samir, the Seller of Dreams" by Daniel Nayeri