nonlinear correlation vs curvilinear correlation

nonlinear correlation and curvilinear correlation both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonlinear correlation	Yes	No	No	No
curvilinear correlation	Yes	No	No	No

As nouns, nonlinear correlation and curvilinear correlation are synonyms defined as:

nonlinear correlation and curvilinear correlation: any correlation in which the rates of change of the variables is not constant

Other synonyms of nonlinear correlation include skew correlation.

nonlinear correlation (noun)	curvilinear correlation (noun)
any correlation in which the rates of change of the variables is not constant	any correlation in which the rates of change of the variables is not constant