a sine qua non

(formal)

something that is necessary, especially if you are going to achieve a particular thing (often + of ) The company sees training as the sine qua non of success.

Common Names:

Name	Pronounced	Usage
Jong-Su	jong-soo	Korean
Arnold	['a:nəld]
Spyro	-	Greek
Michelangela	-	Italian
Solveiga	-	Latvian, Lithuanian
Quintin	['kwintin]