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

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

Inflected Forms

Participles

• thinning
  present
• thinned
  past

Conjugated Forms

Present

• thin
  simple
• thins
  simple
• have thinned
  perfect
• has thinned
  perfect
• am thinning
  progressive
• are thinning
  progressive
• is thinning
  progressive
• have been thinning
  perfect progressive
• has been thinning
  perfect progressive

Past

• thinned
  simple
• had thinned
  perfect
• was thinning
  progressive
• were thinning
  progressive
• had been thinning
  perfect progressive

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

The line between giving just enough personal information for a better prompt, and dangerous oversharing, can be thin when you’re interacting with a chatbot.

From MarketWatch • Jul. 1, 2026

The white cloth that was draped over the jeans-maker’s logo was so thin that the coverup practically accentuated the block letters spelling out its name.

From The Wall Street Journal • Jun. 27, 2026

Additionally, when the layers between them are too thin, sometimes this prevents them from switching off when they're supposed to, and this stops the chip from working.

From BBC • Jun. 25, 2026

Researchers examined thin slices of fossil bone under specialized lighting that can reveal growth rings that are difficult to detect using standard methods.

From Science Daily • Jun. 22, 2026

I transferred the Bible in its bag from Betsie’s back to my own; she was so thin it made a visible bump between her shoulders.

From "The Hiding Place" by Corrie ten Boom

Related Words

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