A cubic measurement is the three-dimensional derivative of a linear measure, so a cubic foot is defined as the volume of a cube with sides 1 ft in length.
In metric terms a cubic foot is a cube with sides 0.3048 metres in length. One cubic foot is the equivalent to approximately 0.02831685 cubic metres, or 28.3169 litres.
The volume equivelent to a cube of one millimeter by one millimeter by one millimeter. More often referred to as a microliter as it is a millionth of a liter.