analogus

Analogus is not a standard term in modern English and is typically considered a misspelling or archaic variant of analogous. In contemporary scientific and instructional writing, the preferred form is analogous. The root derives from Latin analogus and Greek analogos, meaning proportionate or corresponding.

In biology, analogous describes features that are similar in function or appearance but do not arise from a common ancestry. Such similarities result from convergent evolution or similar selective pressures. A classic example is the wings of bats and birds: both enable flight, yet they evolved independently in different lineages. By contrast, homologous structures share a common evolutionary origin, even if their current appearances or functions differ—for instance, the forelimbs of humans, cats, whales, and bats.

Analogies also appear in reasoning and communication, where the similarity between two scenarios is used to infer a conclusion about one based on the other. In these contexts, analogy can support arguments or hypotheses but can also mislead if the underlying similarities are superficial.

If encountered in text, analogus is usually a misspelling or an obsolete usage. Most style guides and dictionaries advocate using analogous as the adjective and analogy as the noun.