Orthocarbonic \Or`tho*car*bon"ic\, a. [Ortho- + carbonic.] (Chem.) Designating a complex ether, {C.(OC2H5)4}, which is obtained as a liquid of a pleasant ethereal odor by means of chlorpicrin, and is believed to be a derivative of the hypothetical normal carbonic acid, {C.(OH)4}. [1913 Webster]