sinus

American  

[sahy-nuhs] / ˈsaɪ nəs /

noun

• sinuses
  plural

1. a curve; bend.

2. a curving part or recess.

3. Anatomy.

   1. any of various cavities, recesses, or passages, as a hollow in a bone, or a reservoir or channel for venous blood.

   2. one of the hollow cavities in the skull connecting with the nasal cavities.

   3. an expanded area in a canal or tube.

4. Pathology. a narrow passage leading to an abscess or the like.

5. Botany. a small, rounded depression between two projecting lobes, as of a leaf.

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sinus British  

/ ˈsaɪnəs /

noun

1. anatomy

   1. any bodily cavity or hollow space

   2. a large channel for venous blood, esp between the brain and the skull

   3. any of the air cavities in the cranial bones

2. pathol a passage leading to a cavity containing pus

3. botany a small rounded notch between two lobes of a leaf, petal, etc

4. an irregularly shaped cavity

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sinus Scientific  

/ sī′nəs /

1. A cavity or hollow space in a bone of the skull, especially one that connects with the nose.

2. A channel for the passage of a body fluid, such as blood.

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Other Word Forms

Derived Forms

• sinuslike
  adjective

Inflected Forms

Nouns

• sinuses
  plural

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Etymology

Origin of sinus

1590–1600; < Latin sinus (stem sinu- ) bent or curved surface, curve, fold

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Explanation

A sinus infection is when the sinuses near your nose get clogged and your face aches. Good times. That’s the kind of sinus people talk about, but a sinus is any kind of space, cavity, or passage in a person's body. When you hear the word sinus, you probably think of the sinuses that can become infected if you have a bad enough cold. You might get a sinus headache when your nose is stuffed up, for example. There are many other sinuses in your body, believe it or not, from the cavernous sinus in your skull to the renal sinuses in your kidneys. The word sinus means "bend, fold, or curve" in Latin.

Example Sentences

See Examples For:

sinus sinuses

“Early on, some families seemed mildly symptomatic, complaining of headaches, scratchy throats and sinus issues,” she said.

From The Wall Street Journal ● Sep. 23, 2026

Her pulmonologist and his team wrote several letters, some of which included charts to show how a combination of Pulmozyme and other therapies had helped prevent lung and sinus infections for Noonan.

From MarketWatch ● Aug. 13, 2026

The seeds of Scott’s journey into offshore medical treatments can be traced to about 2002, when he began to experiment with fasting as a way to prevent persistent sinus infections.

From Slate ● Mar. 30, 2026

A common respiratory bacterium that typically causes pneumonia and sinus infections may also play a role in Alzheimer's disease.

From Science Daily ● Feb. 21, 2026

Not made freaks: not men covered head to toe in tattoos, not women who regurgitate wallets and lightbulbs on command, not moss-haired girls or men who pound stakes into their sinus cavities.

From "Water for Elephants" by Sara Gruen

I wanted it so people who are recording can clean out their vocals and sinuses before they sing.

From The Wall Street Journal ● Dec. 22, 2025

In the case of Nanotyrannus, most of the holotype consists of skull material filled with sinuses and other irregular features that make it unsuitable for this type of study.

From Science Daily ● Dec. 9, 2025

This can come from secondary infections like bronchitis, which inflame the airways, or the extra build-up of phlegm in your nose and sinuses.

From BBC ● Dec. 3, 2025

You feel it enter and push deeper into your body, leaving the lining of your nose, sinuses, throat, and lungs alive with irritation.

From Slate ● Jan. 16, 2025

“Just call it what it is, Alter,” Frankie said, looking at me with such sympathy, my sinuses burned.

From "The City Beautiful" by Aden Polydoros

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