'unexplainable' originates from the prefix 'un-' meaning 'not' and the word 'explain,' which comes from Latin 'explanare,' meaning 'to make plain or clear.'

'explanare' transformed into the Old French word 'expliquer,' and eventually became the modern English word 'explain,' with 'un-' added to form 'unexplainable.'

Initially, 'explain' meant 'to make plain or clear,' and 'unexplainable' has consistently meant 'not able to be explained.'