sinus
Meaning of sinus: A sinus is any hollow cavity or channel within the body, a term applied to structures in the skull, heart, and blood vessels.
Definition of sinus
A sinus is a hollow cavity, space, or channel within the body, a general anatomical term applied to several different structures rather than to one single location.
The paranasal sinuses are air filled spaces within the bones of the face and skull that surround the nasal cavity and connect to it through small openings. Other structures also called sinuses include venous sinuses, channels that collect blood draining from the brain, and the coronary sinus, a vessel that collects blood returning from the heart muscle itself.
Because the term sinus describes a general shape rather than a single structure, its meaning depends entirely on context, and inflammation or blockage affecting one type of sinus, such as a paranasal sinus infection, has no direct relationship to a problem affecting a different structure that happens to share the same name.
Used in a sentence
Imaging of the paranasal sinuses was ordered to evaluate the patient's facial pain and congestion.
Good to know
The word sinus describes several unrelated structures, so a sinus infection affecting the paranasal sinuses has no direct relationship to the venous sinuses of the brain or the coronary sinus of the heart despite the shared name.
Word origin
Where “sinus” comes from
Formed from Latin sinus, meaning a curve, fold, or hollow.