arccosine vs circular function

arccosine and circular function both are nouns.

Word	Noun	Adjective	Verb	Adverb
arccosine	Yes	No	No	No
circular function	Yes	No	No	No

As nouns, circular function is a hypernym of arccosine; that is, circular function is a word with a broader meaning than arccosine:

arccosine: the inverse function of the cosine; the angle that has a cosine equal to a given number
circular function: function of an angle expressed as a ratio of the length of the sides of right-angled triangle containing the angle

Other hypernyms of arccosine include trigonometric function.

arccosine (noun)	circular function (noun)
the inverse function of the cosine; the angle that has a cosine equal to a given number	function of an angle expressed as a ratio of the length of the sides of right-angled triangle containing the angle