Source : Webster's Revised Unabridged Dictionary (1913)

Hyson \Hy"son\, n. [Chin. hi-tshun, lit., first crop, or
   blooming spring.]
   A fragrant kind of green tea.

   {Hyson skin}, the light and inferior leaves separated from
      the hyson by a winnowing machine. --M`Culloch.

Source : WordNet®

hyson
     n : a Chinese green tea with twisted leaves