What is a cuboid?

A cuboid is a rectangular prism (a box)
Opposite faces are congruent
Opposite faces are rectangular
6 faces

A cube is a special type of rectangle in that all faces are congruent

Jeff has made a good sketch.

A rectangular prism.
A solid figure bounded by six rectangular faces
A rectangular box.
.. _______
./............./|
/_____.../..|
|...........|...|
|...........|.../
|...........|../
|..____..|./
Sorry not really an artist

You have a picture and a description. Read through the source.

a solid figure which has atleast 4 rectangular sides...

Cuboid
In geometry, a cuboid (also called a rectangular prism) is a solid figure bounded by six rectangular faces: a rectangular box. All angles are right angles, and opposite faces of a cuboid are equal. It is also a right rectangular prism. The term "rectangular or oblong prism" is ambiguous. Also the term rectangular parallelepiped is used.

The square cuboid, square box or right square prism (also ambiguously called square prism) is a special case of the cuboid in which at least two faces are squares. The cube is a special case of the square prism in which all faces are squares.