orthocarbonic

from The Century Dictionary.

• Designating a variety of carbonic acid, C(OH)₄, which contains the maximum number of hydroxyl-groups. It does not exist in the free state.

from the GNU version of the Collaborative International Dictionary of English.

• adjective (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.