| NCRV | National Committee for Radiation Victims |
|---|---|
| NERO | noninvasive evaluation of radiation output |
| NR | do not repeat [Lat. non repetatur]; nerve root; neural retina; neutral red; noise reduction; nonreac... |
| OR | a logical binary relation that is true if any argument is true, and false otherwise; [o]estrogen rec... |
| ORD | optical rotatory dispersion; oral radiation death |