An analogue device is one that operates in a continuous fashion, rather that step-by-step. The opposite is called discrete by scientists and mathematicians, and digital by electronics engineers.
The easiest rule to follow is, if you can count it then it's discrete; if you have to measure it then it's analogue.
For an electronic device, if it's output is on or off, high or low, +ve or -ve, then it's digital. If the output can vary continuously between two limits then it's analogue.