sine qua nonsi·ne qua non
an essential condition, qualification, etc.; indispensable thing; absolute prerequisite
Origin of sine qua nonL, without which not
sine qua non
An essential element or condition: “The perfect cake is the sine qua non of the carefully planned modern wedding” (J.M. Hilary).
Origin of sine qua nonLate Latin sine qua (causa) n&omacron;n, without which (cause) not : Latin sine, without + Latin qua : feminine ablative of qu&imacron;, which + Latin n&omacron;n, not.
(plural sine qua nons or sine quibus non)
sine qua non - Legal Definition
Without which not. Something that is indispensable and upon which something else relies.