I was confused also. Turns out it was a brand name. DryIce Corp and then Dry Ice became the common name for this solid form of carbon dioxide.
In 1924, Thomas B. Slate applied for a US patent to sell dry ice commercially. Subsequently, he became the first to make dry ice successful as an industry. In 1925, this solid form of CO2 was trademarked by the DryIce Corporation of America as "Dry ice", leading to its common name. That same year the DryIce Co. sold the substance commercially for the first time, marketing it for refrigeration purposes. Then others followed.