lack : 普通用词，指部分或完全的不足。
- Her only problem is a lack of confidence.
- Lack of sleep had made him irritable.
- If he fails it won't be for/through lack of effort (= he has certainly tried).
- We won't be going away this year - lack of funds, I'm afraid.
want : 指完全或短缺某物，侧重缺少之物是必需的东西。使用范围比lack窄些。
- For want of anything better to do I watched television for a while.
- If we fail it won't be for want of trying (= we have tried even if we fail).
absence : 指某物根本不存在或完全短缺，或某人虽存在，但未到现场。
- A new manager was appointed during/in her absence.
- She has had repeated absences from work this year.
shortage : 指不足，但侧重达不到规定的，需要的或已知应有的数量。
- There's a shortage of food and shelter in the refugee camps.
- The long hot summer has led to serious water shortages.
scarcity : 指产量不足或缺乏某物难以应付或满足需要。
- the scarcity of skilled workers