Definition of "biquadratic" []

• Of or relating to the fourth degree. (adjective)
• An algebraic equation of the fourth degree. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "He however extended and developed it, and after his pupil Ferrari had discovered the solution of the biquadratic equation by means of the cubic, he felt justified in publishing it."
• "The solution of cubic and of biquadratic equations, at first only in certain particular forms, but later in all forms, was mastered by"
• "[534] Thomas Baker (c. 1625-1689) gave a geometric solution of the biquadratic in his _Geometrical Key, or Gate of Equations unlocked_ (1684)."