disk n.

circular piece of stone or metal plate about 12 inches in diameter, pitched from a fixed spot the greatest possible distance as a gymnastic exercise and an athletic contest, 1650s, from Latin discus "discus, disk," from Greek diskos "disk, quoit, platter," related to dikein "to throw," which is perhaps from PIE *dik-skos-, from root *deik- "to show, pronounce solemnly; also in derivatives referring to the directing of words or objects" [Watkins]; but Beekes says dikein is of Pre-Greek origin. The notion is "to throw" as "to direct an object."

Latinate spelling preferred in British English for most uses of disk (q.v.). American English tends to use it in the musical recording sense (1888); originally of phonograph records, recently of compact discs.