intervertebral disc vs intervertebral disk

intervertebral disc and intervertebral disk both are nouns.

Word	Noun	Adjective	Verb	Adverb
intervertebral disc	Yes	No	No	No
intervertebral disk	Yes	No	No	No

As nouns, intervertebral disc and intervertebral disk are synonyms defined as:

intervertebral disc and intervertebral disk: a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two)

intervertebral disc (noun)	intervertebral disk (noun)
a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two)	a fibrocartilaginous disc serving as a cushion between all of the vertebrae of the spinal column (except between the first two)