| | NGWP | | no gain without pain |
| | NHI | | no humans involved |
| | nhoh | | never heard of her |
| | nhoh | | never heard of him |
| | nhoh | | Never Heard Of Him/Her |
| | NHS | | National Health Service |
| | NHTSA | | National Highway Traffic Safety Administration |
| | NIAA | | No Idea At All |
| | nib | | new in box |
| | NIBT | | Net Income Before Tax |
| | NICBDAT | | Nothing Is Certain But Death And Taxes |
| | NIH | | National Institutes of Health |
| | NIH | | Not Invented Here |
| | NIHL | | noise induced hearing loss |
| | NIHL | | Noise-Induced Hearing Loss |
| | NILF | | Non-Intelligent Life Form |
| | NIMBY | | not in my back yard |
| | NIMBY | | Not In My Backyard |
| | NIME | | Not In My Experience |
| | NiMH | | Nickel metal Hydride |
| | NIR | | Near Infrared, infrared radiation |
| | NIST | | National Institute of Standards and Technology |
| | NIST | | National institute of technology |
| | NITMOI | | necessity is the mother of invention |
| | NITMOI | | Necessity is the mother of invention. |
| | NITMOI | | Necessity is the mother of it |
| | NIW | | Network Installation Wizard |
| | NJROTC | | Navy Junior Reserve Officer Training Corps |
| | NKFDA | | no known food and drug allergies |
| | NKMA | | No Known Medication Allergies |
|