arccos vs inverse cosine

arccos and inverse cosine both are nouns.

Word	Noun	Adjective	Verb	Adverb
arccos	Yes	No	No	No
inverse cosine	Yes	No	No	No

As nouns, arccos and inverse cosine are synonyms defined as:

arccos and inverse cosine: the inverse function of the cosine; the angle that has a cosine equal to a given number

Other synonyms of arccos include arc cosine, arccosine.

arccos (noun)	inverse cosine (noun)
the inverse function of the cosine; the angle that has a cosine equal to a given number	the inverse function of the cosine; the angle that has a cosine equal to a given number