After losing his job, he sank into a depression of hopelessness.

depression 是由前缀 de-（表示"向下"）和词根 press（压）加上名词后缀 -ion 构成。字面意思是"被压下去的状态"，引申为"情绪低落、抑郁"的状态。在心理学上特指"抑郁症"这种心理疾病。