'assertional' originates from Latin, specifically the word 'assertio' (from the verb 'asserere' / 'adserere'), where 'ad-' meant 'to' and 'serere' meant 'to join or bind.'

'assertional' changed from the Middle English/Old French noun 'assertion' (from Latin 'assertio') and eventually became the modern English adjective by adding the suffix '-al' to form 'assertional'.

Initially connected to the Latin sense of 'affirming, joining, or asserting,' it evolved into the modern meaning 'relating to or expressing an assertion.'