Most people have close friends that they consider family, someitmes even closer than actual family members. They call them their other sister, brother, aunt, uncle, cousin or parent.
Your friend marries a member of your family.
You consider your bff a family member.
if you're closer to your best friend than you are to your family members, they are your "friendamily"
Your children call your close friends Aunty and Uncle even though they are not related.
You have people that you think of as your other family members though they are not related. eg. You call your friends parents Mom and Dad.
A person that acts like your friend when it benefits them but would gladly throw you under a bus if it furthered their ends.
Did you hear about that conservation group that secured donations by claiming to collaborate to protect the environment but worked to marginalize groups that file lawsuits to stop pollution? Serious friendamy.
A person you are close with of the same or opposite sex. You may be attracted to this person whose your buddy, and can talk to them about anything. A friendlyn is someone you love more than all your other friendships.