sine qua non
/ˌsɪni kwɑː ˈnəʊn
/ /ˌsʌɪni kweɪ ˈnɒn/noun
An essential condition; a thing that is absolutely necessary: grammar and usage are the sine qua non of language teaching and learning...
- The study subjects obviously are the sine qua nons of a clinical trial.
- Adopt these strategies for putting the sine qua non of job search success - networking - to the test.
- Clearly the first of two sine qua nons is to be able to express one calculated column in terms of another.
Origin
Latin, literally '(cause) without which not'.