arctangent vs arc tangent

arctangent and arc tangent both are nouns.

Word	Noun	Adjective	Verb	Adverb
arctangent	Yes	No	No	No
arc tangent	Yes	No	No	No

As nouns, arctangent and arc tangent are synonyms defined as:

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

Other synonyms of arctangent include arctan, inverse tangent.

arctangent (noun)	arc tangent (noun)
the inverse function of the tangent; the angle that has a tangent equal to a given number	the inverse function of the tangent; the angle that has a tangent equal to a given number