Analog describes something that represents information as a continuously variable signal, such as an analog watch or analog tape, rather than digital data. Analogue is the British spelling and is also used more broadly for something that closely resembles or corresponds to something else, such as an organ that serves the same function in a different species.
The core difference
Analog is the standard spelling for the technical, non-digital sense; analogue is the British spelling and the usual choice for the broader 'close counterpart' sense.
- analog — continuous, non-digital signal or device: He still prefers an analog watch to a digital one.
- analog — something that closely corresponds to another: Sign language has no exact analog for every spoken idiom.
- analogue — something similar to something else, or a structure with a matching function: The wing and the fin are analogues in function, though not in origin.
How to tell them apart
Both words share the same Greek root: analogos, meaning 'proportionate', built from ana- ('up to') and logos ('ratio'). Analog is the trimmed American spelling; analogue keeps the fuller French-influenced form.
A handy way to remember the split is by subject matter rather than meaning alone. In American writing, analog covers both the electronics sense (an analog clock, analog recording) and the 'corresponding thing' sense. In British and international writing, analogue is used across the board, including in biology for a structure that does the same job as one in another organism despite having a different evolutionary origin.
