isogroups

An isogroup is a conceptual tool used in linguistics, particularly in historical linguistics and dialectology, to represent a set of related forms or words that share a common etymological origin and meaning, but have diverged phonetically or morphologically over time. It is not a single word, but rather a collection of cognates found in different languages or dialects. The term "isogroup" emphasizes the shared linguistic ancestry and the gradual divergence that leads to the observed differences.

The study of isogroups is crucial for reconstructing proto-languages and understanding the relationships between them. By comparing the forms within an isogroup, linguists can infer the likely original form of the word in the ancestral language and trace the sound changes and other processes that led to the modern variations. For example, the isogroup containing English "father," German "Vater," and Latin "pater" helps linguists reconstruct the Proto-Indo-European word for "father."

Isogroups are distinct from isoglosses, which are geographical boundaries marking the limits of a particular linguistic feature. While isoglosses deal with spatial distribution, isogroups focus on the historical development and relationships of lexical items across different speech communities. Analyzing isogroups allows for the mapping of linguistic evolution and the identification of shared innovations and retentions within language families.