sinus

noun si·nus \ˈsī-nəs\

: any of several spaces in the skull that connect with the nostrils

Full Definition of SINUS

: cavity, hollow: 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)

See sinus defined for English-language learners

See sinus defined for kids

Origin of SINUS

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

First Known Use: 15th century

Rhymes with SINUS

dryness, finis, highness, Minos, minus, shyness, slyness, spinous, spryness, vinous, wryness

SINUS Defined for Kids

sinus

noun si·nus \ˈsī-nəs\

Definition of SINUS for Kids

: any of several spaces in the skull mostly connected with the nostrils

Medical Dictionary

sinus

noun si·nus \ˈsī-nəs\

Medical Definition of SINUS

: 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