What’s this sinus thing?

I SUFFER very frequent colds, blocked nose and pain in the area below my eyes. My mother took me to the doctor, who said I have sinusitis. My mother, who calls it ‘sinus’, says it is a very common problem. What is this ‘sinus’?

Sinusitis, commonly called “sinus” problem by Malaysians, is the inflammation of the membrane lining of any of your sinuses. (itis = inflammation).