'genealogical' originates from Late Latin/Greek via the noun 'genealogy' (Late Middle English 'genealogie'), ultimately from Greek 'genealogia', where 'genea-' meant 'race, family' and '-logia' (from 'logos') meant 'account' or 'study'.

'genealogia' in Greek passed into Latin as 'genealogia' and Old French as 'genealogie', then into Middle English as 'genealogie' and later formed the adjective 'genealogical' with the suffix '-al'.

Initially, the root referred specifically to an 'account or study of a race or family'; over time it came to denote anything 'relating to the tracing or study of family descent', which is the modern sense of 'genealogical'.