Source : Webster's Revised Unabridged Dictionary (1913)

Expectorant \Ex*pec"to*rant\, a. [L. expectorans, p. pr. of
   expectorare to drive from the breast: cf. F. expectorant.]
   (Med.)
   Tending to facilitate expectoration or to promote discharges
   of mucus, etc., from the lungs or throat. -- n. An
   expectorant medicine.

Source : WordNet®

expectorant
     n : a medicine promoting expectoration [syn: {expectorator}]