Source : Webster's Revised Unabridged Dictionary (1913)

Cube \Cube\ (k?b), n. [F. cube, L. cubus, fr. Gr. ???? a cube, a
   cubical die.]
   1. (Geom.) A regular solid body, with six equal square sides.

   2. (Math.) The product obtained by taking a number or
      quantity three times as a factor; as, 4x4=16, and 16x4=64,
      the cube of 4.

   {Cube ore} (Min.), pharmacosiderite. It commonly crystallizes
      in cubes of a green color.

   {Cube root}. (Math.), the number or quantity which,
      multiplied into itself, and then into the product,
      produces the given cube; thus, 3 is the cube root of 27,
      for 3x3x3 = 27.

   {Cube spar} (Min.), anhydrite; anhydrous calcium sulphate.

Source : WordNet®

cube root
     n : a number that when multiplied three times equals a given
         number