'unclear' originates from the prefix 'un-' meaning 'not' and the word 'clear', which comes from the Latin 'clarus', meaning 'bright, clear'.

'unclear' was formed by adding the prefix 'un-' to the word 'clear', which has been used in English since the Middle Ages.

Initially, 'clear' meant 'bright or shining', but over time, it evolved to mean 'easily understood', and 'unclear' as its opposite.