despair : 普通用词，指因灾难等因素而丧失希望和信心，陷入沮丧，绝望的境地。
- a mood/sense of despair
- They're in (the depths of) despair over/about the money they've lost.
- To her teacher's despair, Nicole never does the work that she's told to do.
- Their fourth year without rain drove many farmers to despair.
desperation : 语气强烈，指因绝望而使人采取无所顾忌的疯狂行动。
- There was a note of desperation in his voice.
- In desperation, they jumped out of the window to escape the fire.
- an act of desperation
depression : 侧重指因遭受重大失利或挫折而产生的低落情绪。
- There was a feeling of gloom and depression in the office when the news of the job cuts was announced.
- I was overwhelmed by feelings of depression.
- I slid into a depression and became morbidly fascinated with death.
disappointment : 多指愿望或期望的落空。
- Get tickets early to avoid disappointment.
- To my (great) disappointment (= sadness), he decided to leave.
- Book early for the show to avoid disappointment.
- To our great disappointment , it rained every day of the trip.
- He found it difficult to hide his disappointment when she didn't arrive.