pinafore

n. [ From Gr. &unr_;, &unr_;, a tablet. So called because it unites with water so as to form tablet-shaped crystals. ] (Chem.) A white crystalline substance related to the glycols, and made from acetone; hence, by extension, any one of a series of substances of which pinacone proper is the type. [ Written also pinakone. ] [ 1913 Webster ]