sinus

[ sahy-nuh s ]

/ ˈsaɪ nəs /

SEE MORE SYNONYMS FOR sinus ON THESAURUS.COM

noun, plural si·nus·es.

a curve; bend.

a curving part or recess.

Anatomy.

any of various cavities, recesses, or passages, as a hollow in a bone, or a reservoir or channel for venous blood.
one of the hollow cavities in the skull connecting with the nasal cavities.
an expanded area in a canal or tube.

Pathology. a narrow passage leading to an abscess or the like.

Botany. a small, rounded depression between two projecting lobes, as of a leaf.

Nearby words

sinuation, sinuiju, sinumbra lamp, sinuosity, sinuous, sinus, sinus arrest, sinus arrhythmia, sinus block, sinus histiocytosis with massive lymphadenopathy, sinus iridum

Origin of sinus

1590–1600; < Latin sinus (stem sinu-) bent or curved surface, curve, fold

Related forms

si·nus·like, adjective

Definition for sinus (2 of 2)

Iridum

[ ir-i-duh m ]

/ ˈɪr ɪ dəm /

noun

Sinus. Sinus Iridum.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for sinus

A fair number explicitly ask for an antibiotic, to cover the possibility that it is “bronchitis” or a “sinus infection.”
Without Education, Antibiotic Resistance Will Be Our Greatest Health Crisis|Russell Saunders|December 19, 2014|DAILY BEAST
Benign secondary headaches include headaches associated with the cold, flu, or sinus infections.
How to Destroy Your Headaches|Dr. Anand Veeravagu, MD, Tej Azad|June 23, 2014|DAILY BEAST
First of all, migraines often are misdiagnosed as sinus headaches.
Why Everything from Frigid Temperatures to Lightning Can Induce Migraines|Caitlin Dickson|January 8, 2014|DAILY BEAST
One of the entries reads: “I spoke with a doctor for a long time about my sinus infections.”
To Dream a Dream: Georges Perec’s Night Visions|Lauren Elkin|December 26, 2013|DAILY BEAST

One such case seen only at autopsy had a rupture of the aorta just above the sinus of Valsalva and died of hemopericardium.
Arteriosclerosis and Hypertension:|Louis Marshall Warfield
If, however, it be normal, the gauze plug already placed between the sinus wall and the overlying bone is left undisturbed.
A System of Operative Surgery, Volume IV (of 4)|Various
The aorta is not independent as in Chitons, but is a sinus like the other channels of the circulation.
Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 2|Various
This is named the sinus, and is distinguished as being angular or rounded, large or small, according to the species.
A Conchological Manual|George Brettingham Sowerby
Internally the pallial line is plain, and the sinus well marked but not deep.
The Sea-beach at Ebb-tide|Augusta Foote Arnold

British Dictionary definitions for sinus

sinus

/ (ˈsaɪnəs) /

noun plural -nuses

anatomy

any bodily cavity or hollow space
a large channel for venous blood, esp between the brain and the skull
any of the air cavities in the cranial bones

pathol a passage leading to a cavity containing pus

botany a small rounded notch between two lobes of a leaf, petal, etc

an irregularly shaped cavity

Word Origin for sinus

C16: from Latin: a curve, bay

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for sinus

sinus

[ sī′nəs ]

n.

A depression or cavity formed by a bending or curving.

A channel for the passage of blood or lymph, without the coats of an ordinary vessel, such as the blood passages in the gravid uterus or in the cerebral meninges.

Any of various air-filled cavities in the bones of the skull, especially one communicating with the nostrils.

A dilatation in a blood vessel.

A fistula or tract leading to a pus-filled cavity.

Science definitions for sinus

sinus

[ sī′nəs ]

A cavity or hollow space in a bone of the skull, especially one that connects with the nose.

A channel for the passage of a body fluid, such as blood.