Source : Webster's Revised Unabridged Dictionary (1913)

Corroborant \Cor*rob"o*rant\ (k?r-r?b"?-rant), a. [L.
   corroborans, p. pr. See {Corroborate}.]
   Strengthening; supporting; corroborating. --Bacon. -- n.
   Anything which gives strength or support; a tonic.

         The brain, with its proper corroborants, especially
         with sweet odors and with music.         --Southey.

Source : WordNet®

corroborant
     adj : used of a medicine that is strengthening