noun
: any of various sinuses (as the maxillary and frontal) in the bones of the face and head that are lined with mucous membrane derived from and continuous with the lining of the nasal cavity
noun
: any of various sinuses (as the maxillary and frontal) in the bones of the face and head that are lined with mucous membrane derived from and continuous with the lining of the nasal cavity
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012