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

Etymology

Origin of sinus

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

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

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

Back pain, difficult childbirth, dental crowding and sinus infections are not random misfortunes.

From Science Daily ● Jul. 11, 2026

El Chapo said he has been unable to get adequate sleep and experiences “near-constant severe sinus, ear, nose, and throat pain,” which he attributed to hot air being frequently pumped into his cell.

From Los Angeles Times ● Jun. 25, 2026

One of her children has developed a sinus condition and another has chronic headaches.

From The Wall Street Journal ● May 18, 2026

Ernest was fighting a chronic sinus infection, his back was aching, and an orthopedic brace that had been made for him fit so poorly it aggravated rather than relieved the pain.

From "Big Science" by Michael Hiltzik

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

The cold air punished my lungs and sinuses to a visionary clearness.

From "The Bell Jar" by Sylvia Plath