'comparableness' originates from Latin via Middle English and Old French, specifically ultimately from the Latin verb 'comparare', where the prefix 'com-' meant 'together' and the root 'par' (from 'parare'/'par') conveyed the idea of 'equal' or 'prepare/match'.

'comparableness' changed from Middle English forms such as 'comparablenes' (influenced by Old French 'comparable' and Medieval Latin 'comparabilis') and eventually became the modern English noun 'comparableness'.

Initially, related forms meant 'able to be compared' or 'capable of being matched'; over time this unchanged core sense developed into the modern noun denoting the state or quality of being comparable.