The Collaborative International Dictionary of English v.0.48:

Diapnoic \Di`ap*no"ic\, a. [Gr. ? outlet for the wind,
   exhalation, fr. ? to blow through; dia` through + ? to blow,
   breathe: cf. F. diapno["i]que.] (Med.)
   Slightly increasing an insensible perspiration; mildly
   diaphoretic. -- n. A gentle diaphoretic.
   [1913 Webster]