A term for friends so close that you consider them family.?

I'm wondering if there is a common "mainland" term to refer to people that you consider "family", that aren't blood or marriage related. I'm not just referring to just close friends, but something closer than that.

I live in Hawaii, and we have two terms we use for it. One is "hanai", which more or less means, informally adopted.

The second term is "calabash".

For example, my Mother's close knit group of friends from before I was born, I consider to be my Aunties and Uncles. Their children, who I grew up with, I consider cousins. We simply refer to each other as cousins. Only is someone asks how we are related, we say we are "calabash cousins".

I obviously know that "hanai" is a strictly Hawaii term. But until recently, I assumed "calabash" was a generally common term in Hawaii as was a well as the mainland. It was recently brought to my attention that "calabash" is also a fairly region specific word.

So is their a term for this on the mainland, or at least different parts of the mainland that mean the same thing? I'd like an easy explanation for people, not from the island, when inquiring about it.