'unsuitably' originates from the prefix 'un-' meaning 'not' and the word 'suitably', which comes from the Latin word 'suitabilis', meaning 'fit or appropriate'.

'suitabilis' transformed into the Old French word 'suitable', and eventually became the modern English word 'suitable', with 'un-' added to form 'unsuitable'.

Initially, it meant 'not fit or appropriate', and this meaning has largely remained the same in modern usage.