The Collaborative International Dictionary of English v.0.48:

Frontignac \Fron`ti*gnac"\, Frontignan \Fron`ti`gnan"\, n. [So
   called from Frontignan, a town in Southern France.]
   1. A sweet muscadine wine made in Frontignan (Languedoc),
      France.
      [1913 Webster]

   2. (Bot.) A grape of many varieties and colors.
      [1913 Webster]