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
Saline sprays can also help loosen mucus and move it out of your sinuses, per Kelley.
Take a steamy shower.
—
Korin Miller, Health, 18 Dec. 2024
Ease Common Winter Health Conditions According to the Mayo Clinic, humidifiers can help with a number of winter woes, including dry sinuses, bloody noses, cracked lips, dry skin, and breathing problems.
—Meghan Overdeep, Southern Living, 13 Dec. 2024
The arid conditions dry out the mucus in your sinuses, which can cause the sinus walls to become swollen or inflamed, while drying out the skin inside the throat and nasal passages.
—Timothy Dale, Better Homes & Gardens, 23 Nov. 2024
Doctors planned to do another transplant after a third round of chemotherapy, but Nicholas continued to experience illnesses and sinus infections.
—Sabrina Weiss, People.com, 13 Dec. 2024
See all Example Sentences for sinus 
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Korin Miller, Health, 18 Dec. 2024
Ease Common Winter Health Conditions According to the Mayo Clinic, humidifiers can help with a number of winter woes, including dry sinuses, bloody noses, cracked lips, dry skin, and breathing problems.
—Meghan Overdeep, Southern Living, 13 Dec. 2024
The arid conditions dry out the mucus in your sinuses, which can cause the sinus walls to become swollen or inflamed, while drying out the skin inside the throat and nasal passages.
—Timothy Dale, Better Homes & Gardens, 23 Nov. 2024
Doctors planned to do another transplant after a third round of chemotherapy, but Nicholas continued to experience illnesses and sinus infections.
—Sabrina Weiss, People.com, 13 Dec. 2024
See all Example Sentences for sinus
Dictionary Entries Near sinus
Cite this Entry
“Sinus.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/sinus. Accessed 10 Jan. 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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