There are multiple definitions:

1. National Postdoctoral Association(English)

   • Education, Organizations (documentation)

2. nonperfusion area(English)

   • results when a first- or second-order retinal vein focally occludes at an arteriovenous crossing
   • BRVO
   • Ophthalmology
   • https://doi.org…598-019-42982-5

3. non-polluted area(English)

   • EIMD, YYIRT1
   • Air pollution, Hematology, Clinical chemistry, Environment, Pollution and health
   • https://doi.org…28.2017.1325896

4. non-planarity angle(English)

   • calculated by computational analysis. MAAi is more dynamic in response to loading interventions than ACI and NPA
   • ACI, BSA, MAAi
   • Biophysics, Cardiology
   • https://doi.org…4814/phy2.15665

5. nasopharyngeal aspirate(English)

   • HKU1
   • Diagnostics, Respiratory system, ENT
   • https://doi.org…093/ofid/ofx052