Definition

1. Noun:
   • A cavity or hollow space: In anatomy, a "sinus" is an air-filled cavity within a bone, especially in the skull.
   • A channel or passage: In anatomy, a "sinus" can also refer to a wide channel for blood that lacks the typical lining of a blood vessel.
   • An abnormal tract: In medicine, a "sinus" is an abnormal, infected passageway from an abscess to the body's surface.

Examples of Usage

• Noun:
  • The doctor said my sinus was inflamed, causing facial pain.
  • The dural sinus is a major channel for venous blood in the brain.
  • The infection led to the formation of a draining sinus on the skin.

Advanced Usage

• "Sinus rhythm": The normal, regular rhythm of the heart.
  • The patient's electrocardiogram showed a normal sinus rhythm.
• "Sinus headache": A headache often caused by pressure in the paranasal sinuses.
  • Her cold was accompanied by a painful sinus headache.

Variants and Related Words

• Sinusitis (n): Inflammation or infection of the sinuses.
  • Acute sinusitis often follows a common cold.
• Sinusoid (n): A small, irregular blood vessel found in certain organs; mathematically, a curve described by the sine function.
  • Liver tissue contains many sinusoids.
• Paranasal sinuses (n phrase): The collective term for the sinuses connected to the nasal cavity.
  • The maxillary sinuses are the largest of the paranasal sinuses.

Synonyms

• Cavity: A hollow space within the body.
• Passage: A channel or duct in the body.
• Fistula: An abnormal connection between two hollow spaces (a more specific medical term often related to 'sinus').

Related Phrases

• To drain a sinus: A medical procedure to remove fluid from an infected sinus tract.
  • The surgeon had to drain the sinus to treat the abscess.
• Sinus congestion: The blockage of the sinus cavities, typically with mucus.
  • Allergies can cause severe sinus congestion.

Related Idioms

(Note: The word "sinus" itself is highly technical and is not commonly used in idiomatic expressions. The idioms below are related to the condition of the sinuses.) - "A head full of sinuses": A humorous or colloquial way to describe feeling severe sinus pressure or congestion. - With this cold, I feel like I have a head full of sinuses.

Noun

1. a wide channel containing blood; does not have the coating of an ordinary blood vessel
2. any of various air-filled cavities especially in the bones of the skull
3. an abnormal passage leading from a suppurating cavity to the body surface