'umpire' originates from Old French, specifically the word 'nonper' (Middle English 'noumpere'), where 'non-' meant 'not' and 'par' (or 'pair') meant 'equal'.

'umpire' changed from Middle English 'noumpere' (from Old French 'nonper'); through rebracketing of the phrase 'a noumpere' -> 'an oumpere', the initial 'n' was lost and the word eventually became the modern English 'umpire'.

Initially it meant 'an arbiter' or 'one not equal to the parties' (a judge or mediator); over time it came to mean specifically 'an official who enforces rules and makes decisions in sport'.