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
Products with elderberry, mullein and turmeric can all help with inflammation, sinus issues and congestion.
—
Christopher Murray, FOXNews.com, 25 Mar. 2025
Possible side effects include headache, flushed skin, nasal congestion, indigestion, sinus infection, flu-like symptoms, dizziness, nausea, and back pain.5
Stendra
Like other PDE-5 inhibitors, Stendra begins working within 30 minutes.
—Mark Gurarie, Health, 14 Mar. 2025
Research suggests that bromelain has anti-inflammatory properties and helps ease sore throats and clear sinuses.
—Julie Marks, Verywell Health, 10 Mar. 2025
From ear and sinus pressure to dehydration due to the dry circulating air, rarely are these physiologic changes detrimental to pet health.
—Katie Liu, Discover Magazine, 4 Mar. 2025
See All Example Sentences for sinus
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Christopher Murray, FOXNews.com, 25 Mar. 2025
Possible side effects include headache, flushed skin, nasal congestion, indigestion, sinus infection, flu-like symptoms, dizziness, nausea, and back pain.5
Stendra
Like other PDE-5 inhibitors, Stendra begins working within 30 minutes.
—Mark Gurarie, Health, 14 Mar. 2025
Research suggests that bromelain has anti-inflammatory properties and helps ease sore throats and clear sinuses.
—Julie Marks, Verywell Health, 10 Mar. 2025
From ear and sinus pressure to dehydration due to the dry circulating air, rarely are these physiologic changes detrimental to pet health.
—Katie Liu, Discover Magazine, 4 Mar. 2025
See All Example Sentences for sinus
Cite this Entry
“Sinus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sinus. Accessed 6 Apr. 2025.
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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