/kith'/ or /kay'-iee-tee-aitch'/ (proper noun) Abbreviation for Kids In The Hall, a sketch-comedy troupe from Canada who hosted a television show of the same name in the 1980's and 1990's.
The closest single word to describe someone who's like family to you, etymologically derived from a word meaning "relative". More commonly, the word is used for friends, but it can also be used this way.
"This is Adam, my kith."
"Friend, right?"
"No, he's like family to me. Kith is easier and more serious to use than 'brother from another mother', in my opinion."