Definition of sine qua non in US English:

sine qua non

noun

  • An essential condition; a thing that is absolutely necessary.

    ‘grammar and usage are the sine qua non of language teaching and learning’
    • ‘Clearly the first of two sine qua nons is to be able to express one calculated column in terms of another.’
    • ‘The study subjects obviously are the sine qua nons of a clinical trial.’
    • ‘There are three sine qua nons of guerilla warfare.’
    • ‘Adopt these strategies for putting the sine qua non of job search success - networking - to the test.’
    • ‘This practice, one of the sine qua nons of Hungarian rural life, has lost much of its original sacral, ritual meaning.’
    necessity, essential item, necessary item, prerequisite, requisite, requirement, need
    fundamentals, basics, rudiments, principles, first principles, foundations, preliminaries, groundwork
    View synonyms

Origin

Latin, literally ‘(cause) without which not’.

Pronunciation