www.alphadictionary.com

since we just discussed "quality",
and to add some life to this monopolized site:


qua

\KWAH\
in the capacity or character of : as
-The school gym qua dance floor was where Oscar and Nanette fell in love.

qua," a term that comes to us from Latin. It can be translated as "which way" or "as," and it is a derivative of the Latin "qui," meaning "who."

Also known as that without which you cannot have a sine qua non.

Might throw in "quiddity" to compare with "quality".