sinus

Estimated CEFR level: C2 — Proficiency

Estimated from word frequency; not an official CEFR classification.

Definition

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

Learned borrowing from Latin sinus (“a bent surface, curve, hollow”). Doublet of sine.

Carmanicus Sinus: the Gulf of Ormuz. — The Bakhtyār Nāma: A Persian Romance, Unknown
Sinus strictly signifies "a bending," especially inwards. — The Germany and the Agricola of Tacitus, Cornelius Tacitus
My lingering cold had miraculously vanished, inflamed sinuses and all. — Life Blood, Thomas Hoover

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