WordNet sense 1 (something with a round shape like a flat circular plate):

disk, saucer

WordNet sense 2 ((computer science) a memory device consisting of a flat disk covered with a magnetic coating on which information is stored):

magnetic disk, magnetic disc

WordNet sense 3 (sound recording consisting of a disk with a continuous groove; used to reproduce music by rotating while a phonograph needle tracks in the groove):

platter, record, record, phonograph record, phonograph recording