'dendrological' originates from Greek, specifically the word 'dendron' (where 'dendron' meant 'tree') and 'logos' (where 'logos' meant 'study' or 'discourse'), with the English adjectival suffix '-ical' attached.

'dendrological' developed from the noun 'dendrology' (from Modern/Neo-Latin formation from Greek elements) and the adjective was formed in English by adding the suffix '-ical' to produce 'dendrological'.

Initially the root terms referred to 'the study of trees' (dendrology); over time the adjective came to mean 'relating to the study of trees or to trees themselves' in English.