D defs.my
Entry 3 senses Webster, 1913

Quadratic

/kwäd-rät'-ĭk/ · Quad·rat·ic · IPA /kwɒdˈɹætɪk/
01 a. Of or pertaining to a square, or to squares; resembling a quadrate, or square; square.
  1. 1.
    Of or pertaining to a square, or to squares; resembling a quadrate, or square; square.
  2. 2.
    Tetragonal.(Crystallog.)
  3. 3.
    Pertaining to terms of the second degree; as, a quadratic equation, in which the highest power of the unknown quantity is a square.(Alg.)