Ossify - to become rigid or inflexible in habits, attitudes, opinions, etc.: a young man who began to ossify right after college. Origin Ossify stems from the Latin word for "bone," os. It entered English in the
Hidebound — narrow and rigid in opinion; inflexible: “a hidebound pedant.” oriented toward or confined to the past; extremely conservative: “a hidebound philosopher.” (of a horse, cow, etc.) having the back and ribs bound tightly by the hide.