'nonexplanatory' originates from the prefix 'non-' (from Latin 'non', meaning 'not') combined with 'explanatory', which comes from Latin 'explanare' (where 'ex-' meant 'out' or 'thoroughly' and 'planare' meant 'to make level/plain').

'explanatory' developed from Latin 'explanare' into medieval/late Latin forms such as 'explanatorius', passed into Old French and Middle English as forms like 'explanatorie'/'explanatory', and later combined with the productive English negative prefix 'non-' to form 'nonexplanatory' in modern English.

Initially, 'explanare' literally meant 'to make level or plain'; over time it came to mean 'to make clear or to explain', and the compound 'nonexplanatory' simply negates that modern sense to mean 'not explanatory'.