Geometric growth can be expressed mathematically by the equation...

The mathematical expression for geometric (exponential) growth is given by $W_1 = W_0 e^{rt}$.

In this equation:
$W_1$ represents the final size (weight, height, number, etc.) after time $t$.
$W_0$ represents the initial size at the beginning of the period.
$r$ represents the growth rate (relative growth rate).
$t$ represents the time of growth.
$e$ represents the base of natural logarithms.

Therefore, $W_1$ stands for the final size.

Answer: final size