The expression of a strong desire for someone else's property is defined as:

The term that best defines the expression of a strong desire for someone else's property is "covet." To covet something means to have an intense longing or craving for something that belongs to someone else. This word carries the connotation of not just wanting something, but wanting it in a way that may imply envy or jealousy. This aligns perfectly with the definition provided in the question.

In contrast, "complaisance" refers to a tendency to be willing to please others or to be compliant, which does not relate to a desire for property. "Damp" signifies a lack of enthusiasm or a physical state of being wet, and does not connect with desire or longing. "Astute" describes someone who is keenly perceptive or shrewd, particularly in practical matters; however, it does not encompass the idea of desiring someone else's belongings. Thus, "covet" is the most accurate choice given its specific relation to desiring what others have.