Disc  n. (also disk esp. Us and in sense 4a) 1 a flat thin circular object. B round flat or apparently flat surface or mark. 2 layer of cartilage between vertebrae. 3 gramophone record. 4 a (usu. Disk; in full magnetic disk) flat circular computer storage device. B (in full optical disc) disc for data recorded and read by laser. [latin *discus]