Urban Dictionary: Definitions by Karl, j, Anderson

Raw Boning

adjective
having little flesh, especially on a large-boned frame; gaunt.

adjective
slim down to be more fit

Example:
Wow, Jon lost about 80 lbs.

He is raw boning, which is good for his health

A family name of some tall, strong, yet fit (sometime skinny)

Example:
He is name is Bob Rawbone, a decent gentleman from U.K.

A bone that is not cooked yet is often used to describe something very thin.

After the surgery, he lost his appetite and as a result, he lost a lot of weight. Poor man, he is as skinny as a raw bone.

For Bob, Mr. Gordon succeeded in capturing a big, rawboned white horse with a gift of astonishing speed.