Ra*ce"mic (r&adot;*sē"m&ibreve;k), a. [Cf. F. racémique. See Raceme.] (Chem.) Pertaining to, or designating, an acid found in many kinds of grapes. It is also obtained from tartaric acid, with which it is isomeric, and from sugar, gum, etc., by oxidation. It is a sour white crystalline substance, consisting of a combination of dextrorotatory and levorotatory tartaric acids. Gregory.