'unclasp' originates from the Old English prefix 'un-' combined with the Middle English verb 'clasp', where 'un-' meant 'not' and 'clasp' meant 'to fasten or hold'.

'unclasp' changed from Middle English forms such as 'unclaspen' and eventually became the modern English word 'unclasp'.

Initially, it meant 'to release from a fastening', and over time the meaning has remained largely the same as the modern sense 'to open or release from a clasp'.