The Collaborative International Dictionary of English v.0.48:

ambrosiac \am*bro"si*ac\ ([a^]m*br[=o]"z[i^]*ak or
   [a^]m*br[=o]"zh[i^]*ak), a. [L. ambrosiacus: cf. F.
   ambrosiaque.]
   Having the qualities of ambrosia; delicious. [R.]"Ambrosiac
   odors." --B. Jonson.
   [1913 Webster]