In a parallelogram, the diagonals bisect each other. This means that point A, where the diagonals WY and XZ intersect, divides each diagonal into two equal parts.
Given that the length of the diagonal WY is 7 centimeters, point A divides WY into two equal segments:
\[ AW = AY = \frac{WY}{2} = \frac{7 \text{ cm}}{2} = 3.5 \text{ cm} \]
Therefore, the length of \( AW \) is 3.5 centimeters.