Source : Webster's Revised Unabridged Dictionary (1913)

Newtonian \New*to"ni*an\, n.
   A follower of Newton.

Newtonian \New*to"ni*an\, a.
   Of or pertaining to Sir Isaac Newton, or his discoveries.

   {Newtonian philosophy}, the philosophy of Sir Isaac Newton;
      -- applied to the doctrine of the universe as expounded in
      Newton's ``Principia,'' to the modern or experimental
      philosophy (as opposed to the theories of Descartes and
      others), and, most frequently, to the mathematical theory
      of universal gravitation.

   {Newtonian telescope} (Astron.), a reflecting telescope, in
      which rays from the large speculum are received by a plane
      mirror placed diagonally in the axis, and near the open
      end of the tube, and thrown at right angles toward one
      side of the tube, where the image is formed and viewed
      through the eyeplace.

   {Newtonian theory of light}. See Note under {Light}.

Source : WordNet®

Newtonian
     adj : of or relating to or inspired by Sir Isaac Newton or his
           science; "Newtonian physics"

Newtonian
     n : a follower of Isaac Newton