Source : Webster's Revised Unabridged Dictionary (1913)

Attenuant \At*ten"u*ant\, a. [L. attenuans, p. pr. of attenuare:
   cf. F. att['e]nuant. See {Attenuate}.]
   Making thin, as fluids; diluting; rendering less dense and
   viscid; diluent. -- n. (Med.) A medicine that thins or
   dilutes the fluids; a diluent.