a.

1. 薄的；细的；瘦的
   She looks thinner than before.

   她看上去比过去瘦了。

2. 稀少的；稀疏的
   He has thin hair.

   他头发稀疏。

3. 稀薄的；淡的
   The air became even thinner when I climbed to the top of the mountain.

   我爬到山顶时，空气变得更加稀薄了。

4. 微弱的
5. 空洞的；浅薄的；不能令人信服的
   Her speech sounded rather thin.

   她的演讲听上去颇为空洞。

6. 【俚】不舒服的，不愉快的

ad.

1. 薄；细；稀；疏；微
   Don't cut the bread too thin.

   别把面包切得太薄。

vt.

1. 使薄；使细；使稀；使瘦；使淡[（+out）]
   Care thinned her cheeks.

   忧虑使她面颊瘦削。

   The wine has been thinned with water.

   这酒已用水冲淡。

2. 【农】间苗[（+out）]

vi.

1. 变薄；变细；变瘦，变稀；变淡[（+out）]
   His hair is thinning.

   他的头发变少了。

adj.

1. having opposite surfaces or sides relatively close together.
   ▸(of a garment or similar item) made of light material.
   ▸(of a garment or fabric) having become less thick as a result of wear.
2. having little flesh or fat on the body.
3. having few parts or members relative to the area covered or filled; sparse.
   ▸not dense or heavy:

   the thin air of the mountains.
4. containing much liquid and not much solid substance.
5. (of a sound) faint and high-pitched.
   ▸(of a smile) weak and forced.
6. lacking substance or quality; inadequate or weak:
   the evidence is rather thin.

adv.

v.

1. make or become less thick.
2. remove some plants from (a row or area) to allow the others more room to grow.
3. Golf  hit (a ball) above its centre.