'terminable' originates from Latin, specifically the Late Latin word 'terminabilis', where the root 'termin-' (from 'terminus') meant 'boundary, limit, end' and the suffix '-abilis' meant 'able to be'.

'terminable' changed from the Late Latin/Medieval Latin 'terminabilis' into Middle French/Medieval English forms and eventually became the modern English adjective 'terminable'.

Initially, it meant 'capable of having a boundary or limit' (i.e. 'capable of being limited'), but over time it evolved into the current common sense of 'capable of being ended or terminated'.