intervertebral disk vs intervertebral disc

intervertebral disk and intervertebral disc both are nouns.

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

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

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

intervertebral disk (noun)	intervertebral disc (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)