si‧nus /ˈsaɪnəs/
noun [countable][
Date: 1400-1500;
Language: Modern Latin;
Origin: Latin, 'curve, fold, hollow place']
your sinuses are the spaces in the bones of your head that are connected to the inside of your nose:
blocked sinuses a sinus infection [TahlilGaran] Dictionary of Contemporary English ▲