The Collaborative International Dictionary of English v.0.48:

Quinary \Qui"na*ry\, a. [L. quinarius, from quini five each,
   akin to quinque five: cf. F. quinaire. See Five.]
   Consisting of five; arranged by fives. --Boyle.
   [1913 Webster]

   Quinary system (Zool.), a fanciful classification based on
      the hypothesis that each group contains five types.
      [1913 Webster]