glottochronology

noun

glot·​to·​chro·​nol·​o·​gy ˌglä-tō-krə-ˈnä-lə-jē 

: a linguistic method that uses the rate of vocabulary replacement to estimate the date of divergence for distinct but genetically related languages

glottochronological

ˌglä-tō-ˌkrä-nə-ˈlä-ji-kəl 

-ˌkrō-

adjective

Word History

Etymology

glotto- + chronology

First Known Use

1953, in the meaning defined above