a. and sb. [a. F. cubique (Oresme, 14th c.), ad. L. cubicus, a. Gr. κυβικός, f. κύβος CUBE.]
A. adj. 1. Of the form of a cube; cubical.
1551. Recorde, Pathw. Knowl., I. Defin., A dye, whiche is called a cubike bodie by geometricians.
1622. Peacham, Compl. Gentl., ix. (1634), 76. If they would double the Altar in Delos, which was of cubique forme.
1710. Lond. Gaz., No. 4691/4. The said Sword [has] the Pummel of a Cubick form.
1874. trans. Lommel’s Light, 56. A cubic vessel the sides of which are made of glass.
b. Min. Applied to certain minerals that crystallize in cubes or similar forms; as cubic alum, alum-stone or ALUNITE; cubic nitre, sodium nitrate.
1782. Withering, in Phil. Trans., LXXII. 336. Cubic nitre.
1791. Hamilton, Berthollet’s Dyeing, I. I. III. ii. 254. A dissertation on cubic alum.
1877. Watts, Dict. Chem., IV. 105. Nitrate of sodium crystallises in obtuse rhombohedrons, which on cursory inspection have very much the aspect of cubes; hence the name cubic saltpetre.
c. Crystallography. Another name for the Isometric system, in which the three axes are equal and mutually at right angles; the cube being a typical form of the system.
1878. Gurney, Crystallogr., 37. Crystals possessing this highest possible degree of symmetry are said to belong to the Cubic or Tesseral System.
2. Mensuration. Of three dimensions; solid; relating to solid content; esp. used with a unit of length, to express the content or volume of a cube whose edge is that unit, as a cubic foot.
1660. Boyle, New Exp. Phys.-Mech., xvii. 116. We may … define, either in weight or cubick measures the Cylinder of Quick-silver.
1751. Labelye, Westm. Br., 87. The two Middle Piers … contain full 3000 cubic Feet.
1812–6. Playfair, Nat. Phil. (1819), I. 13. The weight of a cubic inch of water.
1869. E. A. Parkes, Pract. Hygiene (ed. 3), 125. For sick persons the cubic space should be more than for healthy persons.
3. Arith., Alg., etc. Relating to or involving the cube or third power of a quantity; of three dimensions, of the third degree.
As † cubic number = CUBE number: † cubic root = CUBE root; cubic equation, an equation of the third degree; cubic curve, a curve represented by an equation of the third degree.
1551. Recorde, Pathw. Knowl., II. Pref. Extraction of rootes both square and cubike.
1594. Blundevil, Exerc., I. xxvi. (ed. 7), 59. A Table containing both the square numbers and Cubique numbers of every Root.
1727–51. Chambers, Cycl., Cubic equation is an equation wherein the unknown quantity is of three dimensions. Ibid., s.v. Curve, One [curve] commonly called the cubic parabola.
1885. Watson & Burbury, Math. Th. Electr. & Magn., I. 179. The system leads to a cubic equation in ε.
B. sb. (ellipt. use of the adj.)., Math. a. A cubic expression or equation. b. A cubic curve.
1799. Wilson, in Phil. Trans., LXXXIX. 301. The rest produce cubics, or cubic-formed sixth powers.
1806. Robertson, Ibid. XCVI. 310. A cubic, or an equation of three dimensions.
1882. in Athenæum, 15 April, 479/3. On Polygons circumscribed about a Cuspidal Cubic.
