An apparatchik (Russian: аппара́тчик) was a full-time, professional functionary of the Communist Party of the Soviet Union or the Soviet government apparat (аппарат, apparatus), someone who held any position of bureaucratic or political responsibility, with the exception of the higher ranks of management called nomenklatura.
James Billington describes an apparatchik as "a man not of grand plans, but of a hundred carefully executed details.
Thus, the term apparatchik, or "agent of the apparatus" was usually the best possible description of the person's profession and occupation.
According to Collins English Dictionary the word can mean "an official or bureaucrat in any organization".
[6] According to Douglas Harper's Online Etymology Dictionary, the term was also used in the meaning "Communist agent or spy", originating in the writings of Arthur Koestler, c. 1941.