The Collaborative International Dictionary of English v.0.48:

Quinic \Quin"ic\, a. [See Quinine, and cf. Kinic.] (Chem.)
   Pertaining to, derived from, or connected with, quinine and
   related compounds; specifically, designating a nonnitrogenous
   acid obtained from cinchona bark, coffee, beans, etc., as a
   white crystalline substance. [Written also chinic,
   kinic.]
   [1913 Webster]