best friend dictionary noun [C]
UK /ˌbest frend ˈdɪk.ʃᵊn.ᵊr.i/ US /ˌbest frend ˈdɪk.ʃᵊn.er.i/
a set of inside jokes and made-up words and phrases used by close friends

You know you’re bonded with your best friend when you develop words and phrases of your own, almost like a secret language. On TikTok, this tradition has been dubbed the “best friend dictionary” and it already has millions of views … The best friend dictionary is iconic, but even more impressive is how quickly everyone partaking in this trend seems to know the definitions.
[bustle.com, 14 May 2024]

friendflation noun [U]
/frendˈfleɪ.ʃᵊn/
the rising cost of going out with friends

Can you put a price on friendship? Apparently you can, and it isn’t cheap. The rising cost of socialising, known as “friendflation”, is “becoming a serious pressure point” for many adult friendships, said The Mirror. “Birthdays aren’t just a few drinks at the pub, they’re weekends away, lavish brunches or fancy dinners”, and “even going for a coffee is nearly a fiver”.
[theweek.com, 1 October 2025]

medium friend noun [C]
/ˈmiː.di.əm ˌfrend/
someone who is closer than an acquaintance but not a very close friend

I personally don’t think that it makes sense to go around calling people medium friends to their face. This term is more about internal taxonomy so that you can name and understand the phenomenon without feeling like you’re the only person experiencing this or feeling bad for it.
[reeswrites.com, 1 June 2025]

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