'inseparability' originates from Latin, specifically from the adjective 'inseparabilis', where the prefix 'in-' meant 'not' and 'separare' meant 'to separate'; the noun was formed by adding the suffix '-ity' (from Latin '-itas').

'inseparabilis' (Latin) passed into Old French/Medieval Latin forms and into Middle English as 'inseparable' (adjective); the abstract noun 'inseparability' developed later by combining the adjective with the Latin-derived nominal suffix '-ity'.

Initially, it meant 'not able to be separated' and over time retained this core meaning while extending to abstract and technical senses (e.g., mathematical or physical nonseparability).