letdown

A decrease, decline, or relaxation, as of effort or energy.

A disappointment.

The descent made by an aircraft in order to land.

A physiological response in lactating females, activated usually in response to sucking or crying by an infant, in which milk previously secreted into the alveoli of the breasts is released into the ducts that lead to the nipple.

Alternative form of let-down.

a feeling of dissatisfaction that results when your expectations are not realized