'nonarbitrable' originates from modern English, formed by prefixing 'non-' (from Latin 'non', meaning 'not') to 'arbitrable' (from 'arbitrate').

'arbitrable' comes from Latin roots such as 'arbiter'/'arbitrare' via Old French and Middle English into the verb 'arbitrate'; the negative formation 'nonarbitrable' is a modern English creation using the productive prefix 'non-'.

Initially related words meant 'to act as a judge or consider' (from Latin 'arbiter'/'arbitrare'); over time the sense narrowed to 'capable of settlement by arbitration' and 'nonarbitrable' now means 'not capable of settlement by arbitration'.