Metonic year

from The Collaborative International Dictionary of English v.0.48

Metonic \Me*ton"ic\, a. [Cf. F. m['e]tonique.]
   Pertaining to, or discovered by, Meton, the Athenian.
   [1913 Webster]

   {Metonic year} or {Metonic cycle}. (Astron.) See under
      {Cycle}.
      [1913 Webster] Metonymic