Spelling of Disc - Disk

The earlier word is disk, which came into the English language in the middle of the 17th century, and (probably following pre-existing words such as risk) it was spelled with a k. The spelling disc was introduced in the 18th century, following an increasing tendency to base the spelling of words on their roots: in this case the Latin word discus and the Greek word δισκος (note that kappa in Greek is usually transliterated by c rather than k). In the 19th century, disk became the conventional spelling for audio recordings made on a flat plate, such as the gramophone record; this usage gave rise to the modern term disc jockey. Early BBC technicians differentiated between disks (in-house transcription records) and discs (the colloquial term for commercial gramophone records, or what the BBC dubbed CGRs).