• Of or regarding the 4th degree.
• He however extended and developed it,…
• equation
• quartic

• Of or regarding the 4th degree.
• Of a polynomial expression, involving only the 2nd and 4th capabilities of a variable, as x4 + 3x2 + 2. Sometimes extended to any expression relating to the 4th energy of adjustable (but no higher abilities), as x4 − 4x3 + 3x2 − x + 1.
• Of or regarding the biquadrate, or fourth energy.
• of or regarding the 4th energy
• noun:
• An algebraic equation associated with 4th level.