'explainability' originates from Latin and later English word-formation, specifically from the verb 'explain' + the noun-forming suffix '-ability', where 'ex-' meant 'out' or 'thoroughly' and Latin 'planare' meant 'to make level or plain'; the suffix '-ability' (via Old French/Latin '-abilitas') meant 'capacity' or 'ability'.

'explainability' changed from Latin 'explanare' → Old French/Anglo-French forms (e.g. 'esplaner') → Middle English 'explainen' (verb) → modern English 'explain', and the abstract noun was formed with the suffix '-ability' (from Latin '-abilitas' through Old French and Middle English) to create 'explainability'.

Initially, the root (Latin 'explanare') carried the sense 'to make level or plain'; over time this shifted to 'to make clear' or 'to make understood', and 'explainability' came to mean 'the capacity or degree to which something can be made clear or understood'—in modern usage it also carries the technical sense of 'interpretability' in AI.