
1) Absolute necessity 2) Indispensable condition 3) Prerequisite 4) Requirement
Found on
https://www.crosswordclues.com/clue/sine-qua-non

(see-nay kwah nahn) prep. Latin for "without which it could not be," an indispensable action or condition. Example: if Charlie Careless had not left the keys in the ignition, his 10-year-old son could not have started the car and backed it over Polly Playmate. So Charlie's act was the sine qua non of the injury to Playmate.
Found on
http://dictionary.law.com/Default.xhtml?selected=1967
[wine] Sine Qua Non (also known as SQN) is a California cult winery known for its Rhône style blends, a tendency to avoid repetition, and a very limited production of wine that is highly difficult to obtain, with 100% of all releases allocated and directly sold to a carefully managed mailing list. The mailing list has by some measures a fi...
Found on
http://en.wikipedia.org/wiki/Sine_Qua_Non_(wine)

Sine qua non (n; lang) or condicio sine qua non (plural: condiciones sine quibus non) refers to an indispensable and essential action, condition, or ingredient. It was originally a Latin legal term for `[a condition] without which it could not be`, or `but for...` or `without which [there is] nothing`. `Sine qua non` causation is the forma...
Found on
http://en.wikipedia.org/wiki/Sine_qua_non

(prep) Sine Qua Non is used to represent an action as the sole reason for occurrence of an incident. The Latin word means 'without which it could not be'. Example. A kid was spoiled because his parent never said no to his demands
Found on
http://www.encyclo.co.uk/local/21213

Sine qua non is Latin for Indispensable condition
Found on
http://www.probertencyclopaedia.com/YR.HTM

sine qua non Without which not; without which nothing. The phrase refers to a necessity, something indispensable; an indispensable condition or qualification for a particular purpose. The original Latin phrase from which they were taken is Sine qua non potest esse ('Without which it is not possible to exist'). There is a little-known plural, sine ...
Found on
http://www.wordinfo.info/words/index/info/view_unit/3481/6

Winery in the Californian wine-growing area of Santa Santa Barbara County owned by Manfred Krankl, who is of Austrian descent; see there.
Found on
https://glossary.wein.plus/sine-qua-non

an absolutely necessary requirement or condition, an indispensable factor
Found on
https://www.businessballs.com/glossaries-and-terminology/latin-terms-and-ph

(Latin) literally without which not; a sine qua non item is one that is unquestionably needed.
Found on
https://www.encyclo.co.uk/local/10135
No exact match found.