'availableness' originates from English, specifically the adjective 'available' plus the noun-forming suffix '-ness'.

'available' developed from Middle English (via Old French 'available'), ultimately tracing back to Latin roots related to 'valere'/'valēre' (to be strong, be worth); 'availableness' was formed in Modern English by adding '-ness' to 'available'.

Initially related to the notion of being of use or value (from Latin 'valēre'), 'available' came to mean 'ready for use or obtainable'; 'availableness' came to denote the state or quality of being available.