n.
An essential element or condition: "The perfect cake is the sine qua non of the carefully planned modern wedding" (J.M. Hilary).
[Late Latin sine quā (causā) nōn, without which (cause) not : Latin sine, without + Latin quā, ablative of quī, which, what, who + Latin nōn, not.]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
