noun, plural di·ach·ro·nies.
  1. Linguistics.
    1. a diachronic approach to language study.
    2. change or development in a linguistic system over a period of time.
  2. historical change.

Origin of diachrony

First recorded in 1955–60; diachron(ic) + -y3
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018