sinus

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noun si·nus \ˈsī-nəs\

Definition of sinus

  1. :  cavity, hollow: such asa :  a narrow elongated tract extending from a focus of suppuration and serving for the discharge of pusb (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 vesselc :  a cleft or indentation between adjoining lobes (as of a leaf or corolla)

Origin and Etymology of sinus

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


First Known Use: 15th century


SINUS Defined for English Language Learners

sinus

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noun si·nus \ˈsī-nəs\

Definition of sinus for English Language Learners

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


SINUS Defined for Kids

sinus

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noun si·nus \ˈsī-nəs\

Definition of sinus for Students

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


Medical Dictionary

sinus

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noun si·nus \ˈsī-nəs\

Medical Definition of sinus

  1. :  a cavity or hollow in the body: asa:  a narrow elongated tract extending from a focus of suppuration and serving for the discharge of pus a tuberculous sinusb (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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