Analog
Analog is a term used in computer-related discussions to describe the lowest conceptual level at which computer components can be examined. (Obviously, in actuality, all computers are 'analog' at their lowest level, since they are built out of electrical circuits.)
As such, things such as voltages, currents, resistors and transistors are the concepts used. Note particularly that voltages are not binary, but can take any value (one of the meanings of 'analog'); this is important in topics such as meta-stability.
Analog computers
The term (sometimes spelled in the old-fashioned form analogue in this usage) is also used to name computing devices, analog computers, in which the fundamental, basic data items have infinitely variable values (voltages, currents etc) - i.e. the meaning above - instead of the limited, discrete, values used in digital computing devices.
