[ˈsʌɪnəs], (Noun)

Definitions:
- a cavity within a bone or other tissue, especially one in the bones of the face or skull connecting with the nasal cavities

- relating to or denoting the sino-atrial node of the heart or its function of regulating the heartbeat
(e.g: sinus rhythm)


Phrases:

Origin:
late Middle English (in the medical sense): from Latin, literally ‘a recess, bend’