Disc or Disk

Disc or disk (pronounced disk)

(1) A phonograph record.

(2) Any thin, flat, circular plate or object.

(3) Any surface that is flat and round, or seemingly so.

(4) In computing hardware, any of several types of media consisting of thin, round plates of plastic or metal, used for external storage.

(5) In zoology and anatomy, any of various roundish, flat structures or parts in the body, especially an intervertebral disc.

(6) In botany, (in the daisy and other composite plants) the central portion of the flower head, composed of tubular florets (especially the middle part of the lip of an orchid).

(7) Any of the circular steel blades that form the working part of a disk harrow.

(8) In mathematics, the domain bounded by a circle.

1655-1665: From the French disque, from the Latin discus, from Ancient Greek δίσκος (dískos) (disk, quoit, platter; a circular plate suited for hurling) from δικεῖν (dikeîn) (to hurl, to launch) from the primitive Indo-European dik-skos from the root deik (to show, pronounce solemnly).  The Proto-Germanic diskaz was also drawn from the Latin and Greek root and was cognate with the Old Saxon disk, the Old Dutch disc (Dutch dis (table)), the Old High German tisc (German tisch (table)) and the Old Norse diskr (plate).

The sense of "phonograph disk" dates from 1888 and discophile was used to describe enthusiasts for gramophone recordings from 1940.  Disk jockey as a term to describe those on radio who broadcast music from records was first recorded 1941; it became dee-jay is 1955 and was further truncated to DJ in 1961; the video version "veejay" is from 1982 but never really caught on.  Disk-drive is from 1952 although disk was first noted in the context of computing in 1947.  Disc brakes were first developed in the late nineteenth century, began to be used on cars at scale in the 1950s and were widely widely available early in the next decade.  The first compact disc (CD) was released in 1982, the digital versatile disc (DVD) in 1995 and the BluRay (BD) disc in 2006.

Disk or Disc

LP album cover; the LP was the final evolution of the traditional phonographic disk.  This cover is memorable but fake, it is a fake disk.

Although both the Latin and Greek spellings have endured, there is in English no formal rule for the use of disc & disk and the two are often used interchangeably.  Even within industries or in countries, there is no consensus on the difference but there are conventions.  Historically the Latinate form was preferred in the British Empire and the Greek in the US but the advent of disk as the preferred use in the computing industry from the 1940s spread worldwide although, as a point of deliberate differentiation, disc was adopted for the new optical hardware (CD, DVD and BluRay).  The distinction is maintained still; mechanical devices are diskettes or hard disks whereas the optical are all discs.

The newer form of storage is solid state and the devices are properly called semiconductor storage devices (SSD) but are more typically referred to (wrongly and presumably influenced by the SSD acronym) as  solid-state disks, or solid-state drives even though SSDs don't have the rotating disk or the drive mechanism which powers the movable read–write heads used with hard disk drives (HDD) and floppy disks (FDD); even among those who understand the difference, the habits of old die hard.  So, the SSD has neither disk nor drive but does require, somewhere in the system, a software driver.

Lindsay Lohan music albums on CD: Speak (2004) and A Little More Personal (RAW) (2005, both released by Casablanca Records.

Although the use in IT greatly increased use of disk, even before the debut of optical media, there was never any indication disc would become extinct.  Except where specifically defined as a brand-name or trademark (such as the CD), both are likely to continue to be used interchangeably with regional and perhaps even generational variations.  Most style guides, even those which provide prescriptive lists, acknowledge this and suggest regardless of the form(s) users choose, what matters is to maintain consistency.  Rotating disks and discs are anyway vanishing from computer hardware so the influence of the industry's conventions of use will presumably diminish.