I was having an argument with someone on the correct spelling of the word.

So it's "disc" right?

No. It's dick. Get a dictionary.

Hard drive disk
Floopy disk
Ram disk

Blue ray disc
compact disc
dvd disc

disc

From http://en.wikipedia.org/wiki/Spelling_of_disc

Disc and disk are the two alternative spellings of the descriptive word for things of a generally thin and circular geometry. These variations are due to the way in which the words originated. The discussion here somewhat focuses on how the word applies to data storage media. See this page for other meanings.

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, disc 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.^[1] 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).^[2]

By the 20th century, the c-spelling was more popular in British English, while the k-spelling was preferred in American English. In the 1950s, when the American company IBM pioneered the first hard disk drive storage devices, the k-spelling was used. Consequently, in computer jargon today it is common for the k-spelling to refer mainly to magnetic storage devices (particularly in British English, where the term disk is sometimes regarded as an abbreviation for diskette, a much later word).

Some latter-day storage device manufacturers prefer the c-spelling. In 1979 the Dutch company Philips, along with Sony, developed the compact disc medium; here, the c-spelling was chosen. The c-spelling is now used consistently for optical media such as the compact disc and similar technologies;^[3] Apple Inc. considers this usage to be official.^[4]

^^^^ I'm way too old to be so immature. Sorry.

They are both right.

I use Disc more often but disk for floppy disk

dlúthdhiosca

thats Gaelic =D

They are both right depending on context, for example a dvd or cd is a disc whereas a hard drive or floppy use disk.