'insole' originates from English, formed from the prefix 'in-' plus the noun 'sole', where 'in-' meant 'inside' and 'sole' ultimately comes from Latin 'solum' meaning 'ground' or 'bottom'.

'insole' was created in modern English by compounding 'in-' with 'sole' (with 'sole' coming via Old French from Latin 'solum'); the compound use referring specifically to the inner bottom of footwear is attested from the 19th century onward.

Initially, the term referred to the inner bottom or lining of a shoe, and it has largely retained that specific meaning in modern usage.