1. 背阴的;阴凉的;多阴的
    You can describe a place as shady when you like the fact that it is sheltered from bright sunlight, for example by trees or buildings.

    e.g. After flowering, place the pot in a shady spot in the garden...
           花期过后，将花盆放到花园里的背阴处。
    e.g. The rooms are admirably cool and shady after the hot brown monotony of the countryside.
           在乡间经受过持续的暴晒后，房间里显得特别阴凉宜人。

2. (树)成阴的
    Shady trees provide a lot of shade.

    e.g. Clara had been reading in a lounge chair under a shady tree.
           克拉拉一直坐在树阴下的躺椅上看书。

3. 可疑的;鬼鬼祟祟的;不正当的
    You can describe activities as shady when you think that they might be dishonest or illegal. You can also use shady to describe people who are involved in such activities.

    e.g. The company was notorious for shady deals...
           该公司因其不法交易而臭名昭著。
    e.g. Joseph watched a shady-looking bunch playing cards aboard a Mississippi steamer.
           约瑟夫看到一群可疑的人在密西西比河的一艘轮船上打牌。