消沉 (xiāo chén): to sink into despondency; (of morale, willpower etc) to diminish; to plummet

After graduating from university, he sent out many resumes but received no replies, and his mood gradually became despondent; he shut himself in his room all day.

Hearing that the team had lost in the finals, even he, who was always optimistic, felt despondent for several days and did not even want to touch his favorite basketball.

After his business failed, he was extremely despondent for a time and drank to drown his sorrows every day; only with the encouragement of family and friends did he slowly emerge from the shadow.

Being unable to find a job for several months in a row made him very despondent, and he even began to doubt his own abilities.

After learning that she had not been selected, she felt despondent and sat alone by the playground in a daze, refusing to listen to anyone's advice.