Pound cake refers to a type of cake traditionally made with a pound

Pound (mass)

The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...

 of each of four ingredients: flour, butter, eggs, and sugar. The traditional recipe makes a cake much larger than most families can consume, and so the quantity is often changed to suit the size of the cake that is desired. As long as the ratio is preserved, the resulting cake will be identical to that using the traditional recipe.