fourth power vs biquadratic

fourth power and biquadratic both are nouns.

Word	Noun	Adjective	Verb	Adverb
fourth power	Yes	No	No	No
biquadratic	Yes	Yes	No	No

As nouns, fourth power and biquadratic are synonyms defined as:

fourth power and biquadratic: an algebraic equation or function of the fourth degree

Other synonyms of fourth power include biquadrate, quartic.

fourth power (noun)	biquadratic (noun)
an algebraic equation or function of the fourth degree	a polynomial of the fourth degree
	an equation of the fourth degree
	an algebraic equation or function of the fourth degree

fourth power (adjective)	biquadratic (adjective)
	involving the fourth and no higher power of a quantity or degree