sinus

noun

si·​nus ˈsī-nəs 

: cavity, hollow: such as

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

Symptoms can range from mild to severe, sometimes leading to other issues, like an ear or sinus infection. —Lauren Schlanger, Verywell Health, 11 Oct. 2024

Surely someone must have attempted to measure this for the sake of sinus science. —Bethany Brookshire, Scientific American, 9 Aug. 2024

Exposure to smoke can cause coughing, a scratchy throat and irritated sinuses, according to the BAAQMD. —Tom Li, The Mercury News, 9 Aug. 2024

Other people do not develop an allergy but have symptoms when mold irritates their sinuses, lungs, eyes, or skin.2 Whether or not they are caused by an allergy, common symptoms of mold exposure can look similar to common allergies. —Sarah Hudgens, Health, 4 Oct. 2024

Word History

Etymology

Middle English, from Medieval Latin, from Latin, curve, fold, hollow

First Known Use

15th century, in the meaning defined above

Phrases Containing sinus

• carotid sinus
• coronary sinus
• sinus node
• sinus rhythm
• sinus venosus
• urogenital sinus

Kids Definition

sinus

noun

si·​nus ˈsī-nəs 

: a hollow place : cavity

especially : any of several cavities in the skull that usually connect with the nostrils

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