cater-cousin

noun2

1. •
   (figurative) A thing which is closely associated with or related to another thing.
2. •
   (no longer used) A person who, while not being a blood relation, is regarded as close enough to be called a cousin; a (very) close or good friend; a bosom friend.

   • His Master and he (sauing your vvorships reuerence) are scarse catercosins. — 1596