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

People with allergies typically have itchy or watery eyes, puffy eyes, itchy throat, sneezing, runny nose or congestion, and a sinus headache. —Nicole Villalpando, Austin American-Statesman, 5 Dec. 2024

Other symptoms of hidradenitis suppurativa include blackheads and, in severe cases, abscesses and tunnels underneath the skin (known as fistulas or sinus tracts). —Petra Guglielmetti, Glamour, 18 Oct. 2024

Keep your sinuses free-flowing and your home smelling like a fancy yoga studio with a cool mist humidifier that can also diffuse essential oils. —Will Porter, Architectural Digest, 29 Nov. 2024

Using a humidifier to increase the moisture in the air helps to reduce sinus discomfort, while eliminating or minimizing symptoms, such as headaches, sinus pressure, and congestion.4 7. —Timothy Dale, Better Homes & Gardens, 23 Nov. 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