something that bears an analogy to something else
"The architect explained how the building's curved roof was an analog to the rolling hills surrounding the city."
In plain English: An analog is a physical object that represents information using continuous movements, like the hands on an old-fashioned clock.
"The old radio had an analog tuner that glided smoothly along the frequency dial."
Usage: As a noun, analog refers specifically to a device or system that uses continuous physical quantities to represent information, such as a vinyl record or a mechanical watch. Do not use this term to describe a general comparison or similarity between two unrelated things.
in which the value of a data item (such as time) is represented by a continuous(ly) variable physical quantity that can be measured (such as the shadow of a sundial)
"The grandfather clock on the wall keeps perfect analog time, where the sweeping second hand represents each passing moment as a smooth, continuous motion rather than jumping from tick to tick."
In plain English: Analog describes something that works by using continuous physical changes, like the hands on an old clock, instead of digital numbers or electronic signals.
"The watch has an analog face with moving hands instead of digital numbers."
Usage: Use "analog" to describe devices or signals where information is represented by continuously varying physical quantities, such as the hands on a traditional clock. Do not use it to mean "similar" or "comparable," which is the incorrect usage often seen in phrases like "it's all analog."
The word analog entered English in the early 19th century from French, originally describing something that is proportionate or functionally similar. It traces its roots back to Ancient Greek, where it combined elements meaning "up to" and "ratio."