arccosine vs arc cosine

arccosine and arc cosine both are nouns.

Word	Noun	Adjective	Verb	Adverb
arccosine	Yes	No	No	No
arc cosine	Yes	No	No	No

As nouns, arccosine and arc cosine are synonyms defined as:

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

Other synonyms of arccosine include arccos, inverse cosine.

arccosine (noun)	arc 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