Qua is defined as in the function of, or in the capacity of. An example of qua is an assistant manager acting as manager while the manager is out sick; the assistant manager qua manager. Qua is a term that comes from Latin. It can be translated as "which way" or "as," and it is a derivative of the Latin qui, meaning "who." Qua has been serving English in the capacity of a preposition since the 17th century.