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

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

From The Wall Street Journal ● May 18, 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

Ohtani’s symptoms have included chest and sinus “stuff” as well as “a deep cough,” Roberts added.

From Los Angeles Times ● Sep. 3, 2025

They found him in bed with one of his chronic sinus infections, resting up for the Nobel ceremony two days hence.

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

But the palace says the Queen, despite this painful inflammation of the sinuses, still plans to take part in the state visit of President Trump, who will be in Windsor on Wednesday.

From BBC ● Sep. 16, 2025

I can still feel the sinuses in my forehead and the tubes in my lungs swell and burn.

From Slate ● Jan. 16, 2025

Finally, when I have survived the worst, opening my eyes underwater, sniffing water into my sinuses and snorting it out, and even gargling repeatedly to wash out my throat, I’m functional enough to help Finnick.

From "Catching Fire" by Suzanne Collins