'unseal' originates from the prefix 'un-' meaning 'not' or 'opposite of' combined with 'seal', which comes from the Latin word 'sigillum', meaning 'a small image or sign'.

'sigillum' transformed into the Old French word 'seel', and eventually became the modern English word 'seal'. The prefix 'un-' was added to form 'unseal'.

Initially, 'seal' meant 'to fasten or close securely', and 'unseal' evolved to mean 'to open something that was sealed'.