'insertional' originates from Latin, specifically the word 'insertio' (from 'inserere'), where 'in-' meant 'into' and 'serere' (or 'serere' as used in compounds) meant 'to join/put'.

'insertional' changed from Late Latin/Medieval Latin 'insertio' (meaning 'a putting in') into the Middle English/Modern English noun 'insertion', and the adjectival suffix '-al' was later added to form 'insertional'.

Initially, the root meant 'to put in' or 'to join in', and over time derivatives came to mean 'relating to the act or result of putting in', which is the current sense of 'insertional'.