a decrease in volume, force, energy, etc.

a letdown in sales; a general letdown of social barriers.

disillusionment, discouragement, or disappointment

The job was a letdown.

depression; deflation

He felt a terrible letdown at the end of the play.

the accelerated movement of milk into the mammary glands of lactating mammals upon stimulation, as by massage or suckling.

Aeronautics . the descent of an aircraft from a higher to a lower altitude preparatory to making an approach and landing or to making a target run or the like.

noun

advantage , benefit , blessing , boon , satisfaction

noun

anticlimax , balk , bitter pill , blow , chagrin , comedown , disgruntlement , disillusionment , frustration , setback , washout * , discontent , discontentment , dissatisfaction , regret , bathos , disappointment , drawback , slump