Source : Webster's Revised Unabridged Dictionary (1913)

Crotonic \Cro*ton"ic\ (kr?-t?n"?k), a.
   Of or pertaining to, or derived from, a plant of the genus
   {Croton}, or from croton oil.

   {Crotonic acid} (Chem.), a white crystalline organic acid,
      {C3H5.CO2H}, of the ethylene, or acrylic acid series. It
      was so named because formerly supposed to exist in croton
      oil. Also, any acid metameric with crotonic acid proper.

   Note: The acid characteristic of croton oil is tiglic or
         tiglinic acid, a derivative of {crotonic acid}.