analogue

Analogue is the British English spelling for a term that in American English is typically written analog. The word comes from Greek analogos, meaning proportionate or corresponding. In general use, analogue describes something that is similar in function or relationship to something else, or that can stand in for another thing of the same kind. The spelling varies by region: analogue is standard in British English, while analog is preferred in American English.

In science and technology, analogue refers to systems and signals that vary continuously. An analogue signal changes smoothly over time, as opposed to a digital signal that changes in discrete steps. Examples include analogue clocks, vinyl records, and many sensor and control systems that process varying voltages or currents. In electronics and communications, the term denotes circuitry and techniques that operate on continuous values, in contrast to digital electronics.

In biology, analogue describes features that have similar function but not a common origin, arising through convergent evolution. An analogue structure serves the same function in different organisms but is not derived from a common ancestral structure. This is distinguished from homologous structures, which share an evolutionary origin despite possible functional differences.

The word is also used in chemistry and pharmacology to describe chemical analogues— compounds with structures similar to a reference compound and often related biological activity. In everyday language, analogue can simply mean a counterpart or a thing comparable to another.