Real Dictionary

analog
adjective: Analog technology involves measuring, storing, or recording an infinitely variable amount of information by using physical quantities such as voltage.

analog in American English
of a system of measurement in which a continuously varying value, as sound, temperature, etc., corresponds proportionally to another value, esp. a voltage
adjective: of or pertaining to a mechanism that represents data by measurement of a continuous physical variable, as voltage or pressure
noun

analog in British English
noun

analog in Electrical Engineering
adjective: An analog system is a system in which an electrical value, such as voltage or current, represents something in the physical world.