Cinnamic \Cin*nam"ic\, a. [From Cinnamon.]

(Chem.) Pertaining to, or obtained from, cinnamon.

Cinnamic acid (Chem.), a white, crystalline, odorless substance. C6H5.C2H2C2H2.CO2H, formerly obtained from storax and oil of cinnamon, now made from certain benzene derivatives in large quantities, and used for the artificial production of indigo.

Source: Webster's Revised Unabridged Dictionary (1913)