The Collaborative International Dictionary of English v.0.48:

Diaphoretic \Di`a*pho*ret"ic\, Diaphoretical
\Di`a*pho*ret"ic*al\, a. [L. diaphoreticus, Gr. ?: cf. F.
   diaphor['e]tique. See Diaphoresis.]
   Having the power to increase perspiration.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Diaphoretic \Di`a*pho*ret"ic\, n. (Med.)
   A medicine or agent which promotes perspiration.
   [1913 Webster]

   Note: Diaphoretics differ from sudorifics; the former only
         increase the insensible perspiration, the latter excite
         the sensible discharge called sweat. --Parr.
         [1913 Webster]

WordNet (r) 3.0 (2006):

diaphoretic
    adj 1: inducing perspiration [syn: diaphoretic, sudorific]
    n 1: used to produce perspiration