diachronic in British English
(ˌdaɪəˈkrɒnɪk) or diachronistic (daɪˌækrəˈnɪstɪk)
adjectiveof, relating to, or studying the development of a phenomenon through time; historical
diachronic linguistics
Compare synchronic Word origin
C19: from
dia- + Greek
khronos time