maxillary sinus

Definition of maxillary sinus

maxillary sinus

(MAK-sih-LAYR-ee SY-nus)
A type of paranasal sinus (a hollow space in the bones around the nose). There are two large maxillary sinuses, one in each of the maxillary bones, which are in the cheek area next to the nose. The maxillary sinuses are lined with cells that make mucus to keep the nose from drying out.

Source: NCI Dictionary of Cancer Terms