Definition of either/or in US English:

either/or

(also either-or)

noun

  • An unavoidable choice between two alternatives.

    ‘you can give him an ultimatum—an either/or’
    • ‘Make no mistake, that is their choice, however much they and their apologists protest it isn't an either/or.’
    • ‘Well I don't see it as an either/or, I think we can do two things at once.’

Pronunciation