Definition of sinus in English:

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Pronunciation: /ˈsīnəs/


1 (often sinuses) Anatomy & Zoology A cavity within a bone or other tissue, especially one in the bones of the face or skull connecting with the nasal cavities.
Example sentences
  • Your sinuses are hollow spaces within the bones of your face, behind and above your nose.
  • Common wood dust produced in sanding furniture and cabinets is associated with increases in cancer of the nasal cavities and sinuses.
  • The sheep's nasal cavity and sinuses are orientated in a similar fashion to man's.
1.2 Medicine An infected tract leading from a deep-seated infection and discharging pus to the surface.
Example sentences
  • Sinusitis is when the sinuses get infected or irritated and cannot drain mucus as well as they should.
  • Asthma, allergies, or a chronic infection in the sinuses or breathing passages might also be responsible for long-term coughs.
  • Pneumonia, bronchitis, and sinus and ear infections are three examples of complications from flu.
1.3 Botany A rounded notch between two lobes on the margin of a leaf or petal.
2 [as modifier] Physiology Relating to or denoting the sinoatrial node of the heart or its function as a pacemaker: sinus rhythm sinus tachycardia
More example sentences
  • A normal heart rhythm is one in which each heartbeat originates in the sinus node and proceeds normally through the rest of the body's electric conduction system.
  • Sinus dysrhythmia refers to a malfunction of the sinus node, the heart's natural pacemaker.
  • Although this medicine has been used to treat heart failure for more than 200 years, its role in patients with congestive heart failure and sinus rhythm is still debatable.


Late Middle English (in the medical sense): from Latin, literally 'a recess, bend, bay'.

Words that rhyme with sinus

Aquinas, Delphinus, echinus, Linus, Longinus, minus, Plotinus, vinous

For editors and proofreaders

Syllabification: si·nus

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