以下这些形容词均有"瘦的" 的意思
lean：侧重缺少脂肪。既可能是因病而瘦，也可能因饥饿而消瘦。也指身体消瘦，但肌肉结实，身体健康。
slender：指身体细长、体态优美、苗条适中，多用于指女性。
slim：指身体的细长，体重轻不着重外形的优美，可用于不同的性别，常用于减轻体重的人。
slight：指身材又瘦又小。
thin：普通用词，指腰细、骨架窄，常因疾病或疲劳而消瘦。

词组

have a thin time
(Brit. informal)have a wretched or uncomfortable time (英，非正式)过得很不舒服
on thin ice
thin air
used to refer to the state of being invisible or non-existent 无影无踪，了无踪影；不存在
the thin blue line
(informal)used to refer to the police, typically in the context of situations of civil unrest (非正式)（多指社会动荡环境下的）警察
thin end of the wedge
thin on the ground
thin on top
(informal)balding (非正式)头发稀疏的

英语六级真题

A mother who is always complaining about being overweight or old sends the message that women are supposed to be thin and young.

出自-2013年6月阅读原文

But if they are taken regularly, they cause a thinning of the voice muscle.

出自-2013年6月听力原文

Why can't the herd be thinned the old-fashioned way?

出自-2013年12月听力原文

柯林斯高阶英汉双解学习词典释义

ADJ-GRADED

窄的;细的

Something that is thin is much narrower than it is long.
例句
A thin cable carries the signal to a computer... 一根细电缆将信号传送给一台计算机。 James's face was thin, finely boned, and sensitive. 詹姆斯面部瘦削，轮廓分明，容易过敏。
ADJ-GRADED

(人、动物)瘦的

A person or animal that is thin has no extra fat on their body .
例句
He was a tall, thin man with grey hair... 他是个瘦高个，头发灰白。 He is small and very thin and has pale-white skin. 他个头瘦小，肤色苍白。
ADJ-GRADED

(纸、布等)薄的

Something such as paper or cloth that is thin is flat and has only a very small distance between its two opposite surfaces.
例句
...a small, blue-bound book printed in fine type on thin paper... 一本用纸轻薄、字体精细的蓝皮小书 A thin layer of topsoil was swept away. 薄薄的一层表土被冲走了。
ADJ-GRADED

(液体)稀的，淡的

Liquids that are thin are weak and watery.
例句
The soup was thin and clear, yet mysteriously rich... 汤又稀又清，味道却出奇地浓。 They are stirring huge pots of rice and thin vegetable soup over a fire made of charcoal. 他们搅动着架在木炭火堆上的大罐米饭和蔬菜清汤。
ADJ-GRADED

(人群、观众)稀少的，稀疏的

A crowd or audience that is thin does not have many people in it.
例句
The crowd, which had been thin for the first half of the race, had now grown considerably. 比赛前半段观众还稀稀拉拉的，这时明显增多了。
ADJ-GRADED

(微笑)冷淡的，牵强的，不幽默的

A thin smile is one that is not friendly or humorous.
例句
All she could manage was a thin, wan smile. 她极力挤出了一丝勉强的苦笑。
ADJ-GRADED

(衣物)薄的，单薄的

Thin clothes are made from light cloth and are not warm to wear.
例句
Her gown was thin, and she shivered, partly from cold. 她的礼服很薄，浑身在发抖，一半是冻的。
ADJ-GRADED

(论点、解释)浅薄的，不足信的，说服力差的

If you describe an argument or explanation as thin, you mean that it is weak and difficult to believe.
例句
However, the evidence is thin and, to some extent, ambiguous... 然而，这个证据难以令人信服，而且有点模棱两可。 Even if the optimists' theory is true, it still seems a thin argument against reform. 就算乐观主义者的理论是对的，还是不足以阻止改革的进行。
ADJ-GRADED

(声音)尖声尖气的，尖细的

A voice or sound that is thin is high-pitched and not very loud.
例句
Her thin voice rose high in complaint. 她抱怨时抬高了尖细的嗓音。
ADJ-GRADED

(头发)稀疏的

If someone's hair is described as thin, they do not have a lot of hair.
例句
She had pale thin yellow hair she pulled back into a bun. 她把一头稀疏的浅黄色头发向后梳，挽成了个圆髻。
V-ERG

(使)变稀疏

When you thin something or when it thins, it becomes less crowded because people or things have been removed from it.
例句
It would have been better to have thinned the trees over several winters rather than all at one time... 当初要是分几个冬天疏剪树木，会比一下子疏剪完效果好。 By midnight the crowd had thinned. 半夜时分，人群渐渐散去了。
VERB

使（调味汁或液体）变稀薄;使变淡

To thin a sauce or liquid means to make it weaker and more watery by adding another liquid to it.
例句
It may be necessary to thin the sauce slightly... 可能有必要将酱汁稍稍稀释一下。 Aspirin thins the blood, letting it flow more easily through narrowed blood vessels. 阿司匹林可以稀释血液，使其在变窄的血管里更顺畅地流动。
VERB

(男子的头发)变稀疏，脱落

If a man's hair is thinning, it has begun to fall out.
例句
His hair is thinning and his skin has lost all hint of youth. 他的头发开始脱落，皮肤也老化了。
PHRASE

(耐心等)消磨掉，耗尽

If someone's patience, for example, is wearing thin, they are beginning to become impatient or angry with someone.
例句
Parliament has not yet begun to combat the deepening economic crisis, and public patience is wearing thin. 议会还没有着手应对日益严重的经济危机，公众日渐失去了耐心。

英汉词典释义

adj.
薄的; 细的
She should wear a thinner shirt in summer. 夏天她应该穿薄一点的衬衫。
稀的, 稀疏的, 稀少的
I have thin hair. 我头发很稀。
瘦的
There were two girls there, a fat one and a thin one. 那儿有两个姑娘, 一个胖的, 一个瘦的。
弱的, 缺乏力量的, 浅薄的, 微弱的, 尖细的, 有气无力的
His excuse for being late was very thin. 他迟到的借口是无法使人相信的。
vt. & vi.
(使)变稀薄, 使变淡, (使)变稀少, (使)变稀疏, (使)变细
His hair is thinning. 他的头发逐渐稀少了。 He thinned the wine by adding water. 他往酒里加水把它稀释。

英英词典释义

Verb
1. lose thickness; become thin or thinner
2. make thin or thinner;
"Thin the solution"
3. lessen the strength or flavor of a solution or mixture;
"cut bourbon"
4. take off weight
Adjective
1. of relatively small extent from one surface to the opposite or in cross section;
"thin wire""a thin chiffon blouse""a thin book""a thin layer of paint"
2. lacking excess flesh;
"you can't be too rich or too thin""Yon Cassius has a lean and hungry look"-Shakespeare
3. very narrow;
"a thin line across the page"
4. having little substance or significance;
"a flimsy excuse""slight evidence""a tenuous argument""a thin plot"
5. not dense;
"a thin beard""trees were sparse"
6. relatively thin in consistency or low in density; not viscous;
"air is thin at high altitudes""a thin soup""skimmed milk is much thinner than whole milk""thin oil"
7. (of sound) lacking resonance or volume;
"a thin feeble cry"
8. lacking spirit or sincere effort;
"a thin smile"
Adverb
1. without viscosity;
"the blood was flowing thin"

行业词典

土木工程：薄壁结构；thin-wall structure；