a. and sb. [ad. L. type *quadrātic-us: see QUADRATE sb.1 and -IC, and cf. F. quadratique.]
A. adj. 1. Square. rare.
1656. in Blount, Glossogr.
1876. trans. Wagner’s Gen. Pathol., 115. They first assume the quadratic form at a distance of one metre behind the head.
1884. Bower & Scott, De Bary’s Phaner., 107. One epidermal cell which appears in surface view rounded and quadratic.
b. Cryst. Of square section through the lateral or secondary axes; characterized by this form.
1871. Roscoe, Elem. Chem., 215. On boiling this solution the salt … is formed, and may be crystallized in quadratic prisms.
1875. Bennett & Dyer, trans. Sachs’ Bot., 66. The calcium oxalate … crystallises in the quadratic system.
2. Math. Involving the second and no higher power of an unknown quantity or of a variable; esp. in quadratic equation: see EQUATION 6.
1668. Wilkins, Real Char., II. vii. 181. Those Algebraical notions of Absolute, Lineary, Quadratic, Cubic.
1690. Leybourn, Curs. Math., 337. All Quadratick Æquations of this kind … have two Roots.
1706. W. Jones, Syn. Palmar. Matheseos, 128. All Quadratic Equations are reducible to one of these Forms.
1806. Hutton, Course Math., I. 247. A simple quadratic equation, is that which involves the square of the unknown quantity only.
1885. Watson & Burbury, Math. Th. Electr. & Magn., I. 169. If we express every e in terms of the potentials by means of equations … E will be a quadratic function of the potentials.
B. sb. a. A quadratic equation. b. pl. The branch of algebra dealing with quadratic equations.
1684. T. Baker, Geometr. Key, Title-p., Of Linears, Quadratics, Cubics [etc.].
1690. Leybourn, Curs. Math., 337. The three sorts of Mixed Æquations above expressed, are all that can happen in Quadraticks.
1727–41. Chambers, Cycl., s.v., There are several methods of extracting the roots of adfected quadratics.
1827. Hutton, Course Math., I. 256, note. Cubic equations, when occurring in pairs, may usually be reduced to quadratics, by extermination.
a. 1839. Praed, Poems (1864), II. 41. By turns, as Thought or Pleasure wills, Quadratics struggle with quadrilles.
1870. [see ADFECTED].
