'appliableness' originates from English, specifically formed from the adjective 'appliable' with the suffix '-ness'; 'appliable' ultimately derives (via French) from Latin 'applicāre', where 'ad-' (often assimilated as 'ap-') meant 'to' and 'plicāre' meant 'to fold/attach'.

'appliableness' developed in Modern English as a noun built from 'appliable' + '-ness'; 'appliable' comes from Late Latin 'applicāre' (to apply/attach) through Old French forms such as 'appliquer' and Middle English adaptations, which produced English adjectives like 'appliable' and 'applicable'.

Initially the root sense was 'to attach or fold toward' (from Latin 'applicāre'), but over time the derived English formations came to mean 'capable of being applied', and 'appliableness' denotes that quality (i.e., applicability).