dirty: emphasizes the presence of dirt more than emotional reaction to it: children ~ from play; OR stresses meanness or despicable: a little ~ secret.


filthy: carries a strong suggestion of offensiveness and gradually accumulated dirt that besmears and begrimes: a stained, greasy floor, utterly ~; OR obscenity: ~ language. (besmear: 用油粘物弄脏) (begrime: 泥污等弄脏) (stain: 液体等留下的污迹)


foul: implies extreme offensiveness and accumulation of what rots and stints: a ~ smelling open sewer(下水道);  OR disgusting obscenity or loathsome behavior: a record of ~ deeds.


nasty: applies to what is actually foul and repugnant to one expecting freshness, sweetness, or cleanliness: it's a ~ job to clean up after a sick cat. although in practice it is often no more than synonym of unpleasant, disagreeable: his answer gave her a ~ shock. (repugnant令人厌恶的)


squalid: adds to dirty and foul the idea of slovenly neglect: live in ~ poverty; or sordid baseness and dirtiness: a series of ~ affairs. (sordid肮脏卑鄙: dirty and dishonest脏不诚实: sordid details of their relationship他们关系的肮脏细节) （base卑鄙，比mean不高尚贬义重）


dirty脏的: 仅表示有泥污而不强调情绪反应，或不良让人轻视(mean这里是不高尚,是贬义词但贬义不重,所以译成不良) , filthy肮脏: 强调脏到冒犯(即极其讨厌)，或下流淫秽(obscene淫秽: 过度涉黄或暴力，例句to behave obscenely举止下流), foul肮脏: 脏到极端冒犯发腐发臭(rot,stint)或淫秽恶心让人厌恶(disgusting,loathsome)，nasty脏: 事实脏让人厌恶，常仅表示不让人喜欢，squalid肮脏: 增加了邋遢疏于管理的意思，或肮脏卑鄙。


记忆方法：1) 首字母记忆法，DFN想象成DouFuNao豆腐脑，FS想象成FeiShui废水，做豆腐脑剩下的废水<==肮脏。  


          2）filthy和foul意思相同都表示冒犯和污秽，foul只是更强烈表示"极度"。      

             解释squalid的base表示卑鄙(开头发音都是bei)比mean(不高尚)严重些。

          3）肮脏的意思是物质上或道德上不干净纯洁mean either physically or morally unclean or impure.