1A door-knocker having the form of a ring; = sense 3d.
2US Military slang (with reference to the practice amongst graduates of wearing a class ring) an officer who is a graduate of one of the United States military academies.
Origin
Mid 19th century.
Definition of ring knocker in US English:
ring knocker
noun
1A door-knocker having the form of a ring; = sense 3d.
2US Military slang (with reference to the practice amongst graduates of wearing a class ring) an officer who is a graduate of one of the United States military academies.