Word for the day....sine qua non

sine qua non

si·ne qua non

Pronunciation:
\ˌsi-ni-ˌkwä-ˈnän, -ˈnōn also ˌsē-; also ˌsī-ni-ˌkwā-ˈnän\

You can find an audio version of the pronunciation here

Function:
noun

Inflected Form(s):
plural sine qua nons also sine qui·bus non \-ˌkwi-(ˌ)bu̇s- also -ˌkwī-\

Etymology:
Late Latin, without which not
Date:
1602

Definition:
: something absolutely indispensable or essential

Idiom:
An essential element or condition, as in A perfect cake is the since qua non of a birthday party. This phrase is Latin for "without which not" and has been used in English since about 1600. It appears more in writing than in speech.