Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
diachronic is an adjective meaning "used of the study of a phenomenon (especially language) as it changes through time". It carries one recorded sense.
used of the study of a phenomenon (especially language) as it changes through time
“diachronic linguistics”
language
Definitions, synonyms and semantic relations for diachronic come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.