'avocational' originates from Latin, specifically the noun 'avocatio' and the verb 'avocare', where the prefix 'a-' (from Latin 'ab-'/'ad-') meant 'away' and 'vocare' meant 'to call'.

'avocation' came into English from Late Latin 'avocatio' (meaning 'a calling away' or 'diversion') and via the noun 'avocation' the adjective 'avocational' was formed by adding the suffix '-al' in English.

Initially it referred to a 'calling away' or diversion from one's main duties; over time it came to mean a 'hobby' or secondary occupation, and now 'avocational' means 'relating to a hobby or secondary occupation'.