/ˈænəlɒɡ/
[noun] Something that is similar to or works in the same way as something else, especially when one is older or more traditional and the other is newer or digital. In science, it can also mean a compound with a similar structure to another.
Before 'analogue' meant old-fashioned dials and clocks, it simply described anything in the universe that perfectly mirrors something else.
The story of 'analogue' begins in ancient Greece with the word 'analogos', built from two smaller pieces: 'ana', meaning 'up' or 'according to', and 'logos', meaning 'ratio', 'reason', or 'word'. Together they described something that maintains a consistent proportion or relationship — a mathematical concept before it was anything else. Greek mathematicians used it to express the idea that two ratios could mirror each other perfectly, the way 4 is to 8 as 5 is to 10.
Latin absorbed the Greek form almost unchanged, borrowing it as 'analogus', and this was the version that began travelling through the scholarly languages of medieval Europe. By the time it reached English in the seventeenth century, it had passed through medieval Latin scholarly writing, arriving as both the adjective 'analogous' and, slightly later, the noun 'analogue'. The French form 'analogue' — identical in spelling to the English — also exerted a strong pull, since French was the prestige language of science and philosophy at the time.
In its earliest English life, 'analogue' was a technical term belonging to philosophy and biology. Naturalists in particular found it enormously useful. When comparing animals from different species, they needed a word to describe parts that performed the same function but had completely different origins — like a bird's wing and a fish's fin. These were 'analogues' of each other: similar in role, not in ancestry. This was distinct from 'homologue', which described parts sharing the same evolutionary origin, such as a human arm and a whale's flipper.
The truly dramatic shift in the word's meaning came in the twentieth century, and specifically with the rise of computing. Engineers designing early computers made a fundamental distinction between two types of machines. One type used continuously varying physical quantities — electrical voltage, mechanical movement, fluid pressure — to represent information. The other used discrete steps and binary digits. The first type became known as 'analogue' computers, because they worked by analogy: a rising voltage was an analogy for a rising number. The second type became 'digital'. This gave birth to the modern contrast we live with daily.
Once digital technology swept into everyday life through records, clocks, cameras, and telephones, 'analogue' acquired an almost nostalgic warmth. It came to represent everything warm, continuous, and physical — the sweep of a clock hand, the crackle of a vinyl record, the grain of a photograph. The word that once described abstract mathematical ratios in Aristotle's writings now evokes a whole aesthetic and emotional attitude toward older technology. Few words have made so dramatic a journey, from the pure logic of Greek proportion to the warm fuzziness of a spinning record.
Closely related words have spread widely through English from the same root. Greek 'logos' gave English 'logic', 'logistics', and 'catalogue' (Greek 'katalogos', meaning a list or register, via Latin 'catalogus'). The prefix 'ana-' appears in 'analysis' (Greek 'analyein', to unloose, via Latin 'analysis'). And 'analogous', the adjective twin of 'analogue', has lived in English since the 1640s, doing quiet, steady work in science and argument whenever one thing needs to be shown as a fair mirror of another.