What is the Difference Between a Disc and a Disk?

Michael Pollick

For the most part, the words "disc" and "disk" can be used interchangeably to describe flat, rounded objects. The British tend to prefer "disc," and Americans generally use "disk" as their default spelling. In some cases, the spelling with a "k" at the end is based on Germanic origins, and the spelling with a "c" at the end is based on Greek or Latin origins. The use of "disc" or "disk," however, is often simply a matter of preference within a particular field of use. No matter the field or the typical spelling for a particular object, it is not unusual to see the other spelling used, even by respected sources.

"Disc" is often used for anatomical objects, such as optic disc.
"Disc" is often used for anatomical objects, such as optic disc.

The word "disk" entered the popular vernacular first, sometime during the 17th century. By the 18th century, however, there was a movement toward incorporating Latin roots whenever possible. The Latin word discus led to the use of "disc" to refer to thin, circular objects.

In astronomy, the shape of a galaxy might be described as a disc.
In astronomy, the shape of a galaxy might be described as a disc.

Discs or disks appear in fields such as computers, media, science, anatomy and automotive mechanics. Some of these fields primarily use one spelling, and others use both, depending on the specific object. In many fields, the spellings can be used interchangeably.

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"Disc" is commonly used in the context of the spine and spinal injuries like disc herniation.
"Disc" is commonly used in the context of the spine and spinal injuries like disc herniation.

In computers and media, "discs" or "disks" typically refer to storage devices for data, music and videos. Phonographic records were also known as discs, and people who played records on radio stations were called disc jockeys. When optical storage devices were introduced, this spelling carried over into compact discs (CDs) and digital versatile discs (DVDs). Magnetic storage devices often use the spelling with a "k," as seen in floppy disks and computer hard disks.

Jewel cases may be used to prevent scratching of compact discs.
Jewel cases may be used to prevent scratching of compact discs.

Anatomical objects typically use the "disc" spelling. For example, a healthcare professional might refer to a "herniated disc" when a patient has a certain injury to the fibrocartilage between vertebrae in the spine. Other discs in the human body include optic discs in the eyes and placental discs in females.

In computers, disks are used for the storage of data.
In computers, disks are used for the storage of data.

In automotive mechanics, a disc brake is a device that uses friction against a circular metal plate to slow or stop the vehicle's wheel. In astronomy, the shape of a galaxy might be described as a disc. A ring of debris orbiting an object such as a star, on the other hand, typically is referred to as a debris disk.

Compact discs can store data.
Compact discs can store data.

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Discussion Comments

anon989800

The statement "the spelling with a 'c' at the end is based on Greek or Latin origins" is only half-right: There was no "C" in Greek, only the letter "K" (kappa). The "C" is Latin, and is always pronounced with a hard "K" sound in that language (Caesar, for example, is pronounced ""Kaiser" in Latin). The origin of "disc" does come from the Latin word "discus."

recapitulate

I have personally seen the spelling of "disc", rather than "disk", used with almost any medical use of the word. Not only do chiropractors use it to talk about herniated discs, as the article states, but also to describe cervical discs or anything else relating to spinal discs or disc surgery.

elizabeth23

When talking about anything relating to computers, I have only ever seen "disc" used in recent years, with the exception of the "floppy disk" that has now become almost entirely obsolete. Disc drives, compact discs, back-up discs, and any other thing seem to have decided on "disc" as the standardized spelling.

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