The Collaborative International Dictionary of English v.0.48:

Quartic \Quar"tic\, a. [L. quartus fourth.] (Mach.)
   Of the fourth degree.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quartic \Quar"tic\, n.
   (a) (Alg.) A quantic of the fourth degree. See Quantic.
   (b) (Geom.) A curve or surface whose equation is of the
       fourth degree in the variables.
       [1913 Webster]

WordNet (r) 3.0 (2006):

quartic
    n 1: an algebraic equation of the fourth degree [syn:
         biquadrate, biquadratic, quartic, fourth power]