'doctrinally' originates from Latin, specifically the word 'doctrina', where 'docere' meant 'to teach'; the adjective-forming suffix '-al' and the adverbial suffix '-ly' were added to form the modern word.

'doctrinally' changed from Latin 'doctrina' into Old/Medieval French 'doctrine' and Middle English 'doctrine'; the adjective 'doctrinal' developed from 'doctrine' + '-al' in Early Modern English, and the adverb 'doctrinally' was formed by adding '-ly' to 'doctrinal'.

Initially it meant 'teaching' or 'instruction' (from 'doctrina'), but over time it evolved into its current sense of 'relating to doctrine' and adverbially 'in terms of or according to doctrine'.