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

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

Conjugated Forms

Present

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

Past

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

Future

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

Thin margins and less venture-capital money, which is now focused on artificial intelligence and space, has meant smaller players find it hard to stay independent.

From Barron's • May 26, 2026

Thin Lizzy’s name was adapted from the British comic-book character “Tin Lizzie,” a female robot.

From The Wall Street Journal • Mar. 3, 2026

But we also know him as Ziggy Stardust, the alien rock star, or the elegant, worldly Thin White Duke.

From Salon • Jan. 24, 2026

Cult Classics Cinema will screen “Boomerang” on Saturday, “A Thin Line Between Love and Hate” on Feb. 15 and “B.A.P.S.” on March 14 at the Miracle Theater in Inglewood.

From Los Angeles Times • Jan. 23, 2026

Thin and tightly wound, he spoke too quickly for anyone to follow exactly what he was saying.

From "The Big Short" by Michael Lewis

Related Words

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