(US, military, slang) An officer who graduated from a military academy.

plural of ring knocker

plural of nigger-knocker

Alternative spelling of nigger knocker

(UK, simile) Completely black in colour.

A young boy employed to make the base of a saggar from a lump of fireclay, knocking it into a metal ring with a wooden mallet.

plural of saggar maker's bottom knocker

Without a knocker (hinged device for knocking).