'extensibility' originates from Latin, specifically the word 'extensibilis', where 'ex-' meant 'out(ward)', 'tendere' (or 'tend-') meant 'to stretch' or 'to extend', and the suffix '-bilis' meant 'able'.

'extensibility' changed from the Medieval Latin word 'extensibilitas' (formed from 'extensibilis') and eventually became the modern English word 'extensibility'.

Initially, it meant 'ability to be stretched or extended' in a physical sense, but over time it evolved to include the modern sense of 'capacity to be expanded in scope or functionality', especially in technical contexts.