thin

American  

[thin] / θɪn /

adjective

thinner, thinnest

1. having relatively little extent from one surface or side to the opposite; not thick.

   thin ice.

2. of small cross section in comparison with the length; slender.

   a thin wire.

3. having little flesh; spare; lean.

   a thin man.

   Synonyms:

   scrawny, lank, skinny, slender, slim

4. composed of or containing objects, particles, etc., widely separated; sparse.

   thin vegetation.

5. scant; not abundant or plentiful.

   Synonyms:

   meager

6. of relatively slight consistency or viscosity.

   thin soup.

7. rarefied, as air.

8. without solidity or substance; flimsy.

   a very thin plot for such a long book.

   Synonyms:

   weak

9. lacking fullness or volume; weak and shrill.

   a thin voice.

10. without force or a sincere effort.

    a thin smile.

11. lacking body, richness, or strength.

    a thin wine.

12. lacking in chroma; of light tint.

13. Photography. (of a developed negative) lacking in density or contrast through underdevelopment or underexposure.

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adverb

1. in a thin manner.

2. sparsely; not densely.

3. so as to produce something thin.

   Slice the ham thin.

verb (used with object)

thins, present (3rd person singular) thinned, past participle, past thinning present participle

1. to make thin or thinner (often followed by down, out, etc.).

verb (used without object)

thins, present (3rd person singular) thinned, past participle, past thinning present participle

1. to become thin or thinner; become reduced or diminished (often followed by down, out, off, etc.).

   The crowd is thinning out.

thin British  

/ θɪn /

adjective

1. of relatively small extent from one side or surface to the other; fine or narrow

2. slim or lean

3. sparsely placed; meagre

   thin hair

4. of relatively low density or viscosity

   a thin liquid

5. weak; poor; insufficient

   a thin disguise

6. (of a photographic negative) having low density, usually insufficient to produce a satisfactory positive

7. mountaineering a climb or pitch on which the holds are few and small

8. few in number; scarce

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adverb

1. in order to produce something thin

   to cut bread thin

verb

1. to make or become thin or sparse

thin Idioms  

More idioms and phrases containing thin

• into thin air
• on thin ice
• spread oneself too thin
• through thick and thin
• wear thin

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Synonym Usage

Thin, gaunt, lean, spare agree in referring to one having little flesh. Thin applies often to one in an unnaturally reduced state, as from sickness, overwork, lack of food, or the like: a thin, dirty little waif. Gaunt suggests the angularity of bones prominently displayed in a thin face and body: to look ill and gaunt. Lean usually applies to a person or animal that is naturally thin: looking lean but healthy after an outdoor vacation. Spare implies a muscular leanness with no diminution of vitality: Lincoln was spare in body.

Other Word Forms

Derived Forms

• thinness
  noun
• superthin
  adjective
• unthinned
  adjective
• self-thinning
  adjective
• overthin
  adjective
• unthinning
  adjective
• thinly
  adverb
• overthinness
  noun
• overthinly
  adverb

Conjugated Forms

Present

• has thinned
  perfect 3rd person singular
• have thinned
  perfect
• are thinning
  progressive
• is thinning
  progressive 3rd person singular
• am thinning
  progressive 1st person singular
• have been thinning
  perfect progressive
• has been thinning
  perfect progressive 3rd person singular
• thinning
  participle
• thins
  singular 3rd person

Past

• had thinned
  perfect
• was thinning
  progressive singular
• had been thinning
  perfect progressive
• thinned
  simple
• thinned
  participle
• were thinning
  progressive plural

Future

• will thin
  simple
• will have thinned
  perfect
• will be thinning
  progressive
• will have been thinning
  perfect progressive

Etymology

Origin of thin

First recorded before 900; (adjective and adverb) Middle English thyn(ne), Old English thynne; cognate with Dutch dun, German dünn, Old Norse thunnr; (verb) Middle English thynnen, Old English thynnian, derivative of the adjective; compare Middle Dutch dunnen, Old Norse thynna; akin to Old Irish tana, Latin tenuis thin, Greek tany- long

Explanation

Something thin is narrow or not very thick. If you wear thin socks on a cold winter day, your toes might start to feel numb. Thin can describe something that is narrow and slender, like a hair or a thread. It can also describe a layer of something that is not very thick, such as paper. To thin something out is to make it lesser or weaker, like thinning out a sauce by adding water. You can also use this word figuratively. An argument that is not very convincing is thin.

Example Sentences

To create the connectome, researchers sliced a single fruit fly into thousands of extremely thin serial sections.

From Science Daily • Jun. 10, 2026

“A 5% bump, especially in the retail industry where margins are thin, is a big deal,” says Dmitry Mitrofanov, an assistant professor at Boston College’s Carroll School of Management and one of the paper’s authors.

From The Wall Street Journal • Jun. 9, 2026

The fact that it’s best enjoyed piping hot, with steam rising in thin streams from spoonfuls of rice.

From Salon • Jun. 7, 2026

Unlike sorcerer "Koshchei the Deathless", the Kremlin cannot abracadabra coins out of thin air.

From BBC • Jun. 7, 2026

When he turned toward us, holding out his arms for the Kyrie, his hands trembled; his face was pale and thin.

From "Nory Ryan’s Song" by Patricia Reilly Giff

Related Words

• delicate
• fragile
• gaunt
• lean
• meager
• narrow
• skinny
• slim
• small