a
: a narrow elongated tract extending from a focus of suppuration and serving for the discharge of pus
b(1)
: a cavity in the substance of a bone of the skull that usually communicates with the nostrils and contains air
(2)
: a channel for venous blood
(3)
: a dilatation in a bodily canal or vessel
c
: a cleft or indentation between adjoining lobes (as of a leaf or corolla)
Examples of sinus in a Sentence
Recent Examples on the Web
This adjustable blackout mask from Manta comes with freezable cooling eye cups to soothe sinuses and is made with soft fabric that won’t snag.
—
Kristin Canning, SELF, 16 Aug. 2024
The dura can be damaged from head injuries or punctured during surgical procedures involving the sinuses, brain or spine, such as lumbar puncture, epidurals, spinal anesthesia or myelogram.
—Danielle Wilhour, Discover Magazine, 15 Aug. 2024
How Cannabis Use May Influence the Risk of Head and Neck Cancers
The study authors set out to clarify whether heavy cannabis use has any connection to the risk of head and neck cancers, which can develop in the mouth, nose, sinuses, salivary glands, throat, and larynx (voice box).
—Maggie O'Neill, Health, 14 Aug. 2024
Breathing in air pollution can cause inflammation in your nasal and sinus tissues along with postnasal drip.
—Jenny Sweigard, Verywell Health, 1 July 2024
See all Example Sentences for sinus 
Kristin Canning, SELF, 16 Aug. 2024
The dura can be damaged from head injuries or punctured during surgical procedures involving the sinuses, brain or spine, such as lumbar puncture, epidurals, spinal anesthesia or myelogram.
—Danielle Wilhour, Discover Magazine, 15 Aug. 2024
How Cannabis Use May Influence the Risk of Head and Neck Cancers
The study authors set out to clarify whether heavy cannabis use has any connection to the risk of head and neck cancers, which can develop in the mouth, nose, sinuses, salivary glands, throat, and larynx (voice box).
—Maggie O'Neill, Health, 14 Aug. 2024
Breathing in air pollution can cause inflammation in your nasal and sinus tissues along with postnasal drip.
—Jenny Sweigard, Verywell Health, 1 July 2024
See all Example Sentences for sinus
These examples are programmatically compiled from various online sources to illustrate current usage of the word 'sinus.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Dictionary Entries Near sinus
Cite this Entry
“Sinus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sinus. Accessed 7 Sep. 2024.
Copy CitationKids Definition
Medical Definition
sinus
noun
si·nus
ˈsī-nəs 
: a cavity or hollow in the body: as
a
: a narrow elongated tract extending from a focus of suppuration and serving for the discharge of pus
a tuberculous sinus
b(1)
: a cavity in the substance of a bone of the skull that usually communicates with the nostrils and contains air
(2)
: a channel for venous blood
(3)
: a dilatation in a bodily canal or vessel
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