The Collaborative International Dictionary of English v.0.48:
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.
WordNet (r) 3.0 (2006):
adj 1: used of a medicine that is strengthening