Other forms: nasals
Anything nasal relates to the nose, including a nasal voice that you can make by pinching your nose.
Just as optical things relate to the eyes, nasal things relate to the nose. Your nostrils lead to your nasal passages, and if your septum (the middle part of your nose) needed to be repaired, it would require nasal surgery. Also, this word is commonly used to describe a kind of exaggerated, wheezy tone of voice that you can imitate by pinching your nose. Some people's voices are naturally nasal, like the singer Bob Dylan.