clot

American  

[klot] / klɒt /

noun

1. a mass or lump.

2. a semisolid mass, as of coagulated blood.

3. a small compact group of individuals.

   a clot of sightseers massed at the entrance.

4. British Informal. blockhead, dolt, clod.

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verb (used without object)

clotted, clotting

1. to form into clots; coagulate.

verb (used with object)

clotted, clotting

1. to cause to clot.

2. to cover with clots.

   Carefully aimed snowballs clotted the house.

3. to cause to become blocked or obscured.

   to clot the book's narrative with too many characters.

clot British  

/ klɒt /

noun

1. a soft thick lump or mass

   a clot of blood

2. informal a stupid person; fool

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verb

1. to form or cause to form into a soft thick lump or lumps

clot Scientific  

/ klŏt /

1. A soft insoluble mass formed when blood or lymph gels. During blood clotting, white blood cells, red blood cells, platelets, and various clotting factors interact in a cascade of chemical reactions initiated by a wound. When a body tissue is injured, calcium ions and platelets act on prothrombin to produce the enzyme thrombin. Thrombin then catalyzes the conversion of the protein fibrinogen into fibrin, a fibrous protein that holds the clot together. An abnormal clot inside the blood vessels or the heart (a thrombus or an embolus) can obstruct blood flow.

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Other Word Forms

• clottish
  adjective
• declot
  verb
• nonclotting
  adjective
• unclotted
  adjective

Etymology

Origin of clot

before 1000; Middle English; Old English clott lump; cognate with Middle Dutch klotte, German Klotz block, log ( cf. klutz)

Explanation

A clot is a mass of coagulated blood. It's your body's way of repairing itself, stopping blood from flowing and beginning to heal a wound. You can use the noun clot for any liquid that forms a solid lump or mass, though it's usually a medical term specifically related to blood. Some clots are useful, like the ones that form on skin that's been cut, while others — like those that occur inside blood vessels — can be harmful. Clot can also be a verb, meaning to clog or coagulate. The root is the German word Klotz, which means "lump or block."

Example Sentences

But across the country, families — first in smatterings, now in droves — are declining the single, inexpensive injection given at birth to newborns to help their blood clot.

From Salon • May 7, 2026

Sinbad had an ischemic stroke — the result of a blood clot that traveled from his heart to his brain — in 2020.

From Los Angeles Times • Apr. 30, 2026

Maradona, regarded as one of the greatest football players of all times, died in November 2020 at age 60, while recovering at home from surgery for a brain clot.

From Barron's • Apr. 23, 2026

At the Olivos Clinic in Buenos Aires, doctors detected a blood clot on his brain, which was removed during an emergency operation.

From The Wall Street Journal • Apr. 16, 2026

The children moved in a clot down the hill, stomping and pushing and screaming but never straying far from each other.

From "The Undead Fox of Deadwood Forest" by Aubrey Hartman

Related Words

• clotting
• clump
• lump