family-tree theory

[fam-uh-lee tree, fam-lee-]
noun Historical Linguistics.
  1. a theory that describes language change in terms of genetically related languages developing in successive splits from a common parent language, such as Indo-European, as depicted by a family tree diagram.
Compare wave theory.

Origin of family-tree theory

First recorded in 1930–35 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018