dendrochronologynoun [ U ]
uk/ˌden.drəʊ.krəˈnɒl.ə.dʒi//ˌden.droʊ.krəˈnɑː.lə.dʒi/a way of calculating dates and the age of objects by counting the rings that appear inside tree trunks:
Dendrochronology of timbers from the present mansion showed that the roof and part of one wing were built around 1623.