Someone you feel overwhelmingly connected to who definitely isn't your sibling or just a good friend; you would like to spend more time with this person, preferably naked, but your husband and their wife would most certainly frown upon it.
'We are not having an affair!!!! He's my friebling...it's a properdefined term, go look it up!'
The coolest person in your friend group; they're really nice, kind, sweet, and overall just the best person ever. They are what people call saints, and what god calls allies.