"A",
"B",
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P",
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
| n | - | nano (10–9), refractive index |
| NO | - | spectral noise density, sea level refractivity |
| NA | - | numerical aperture |
| NAK | - | negative-acknowledge character |
| NAN | - | niche area network |
| NASA | - | National Aeronautics and Space Administration |
| NATA | - | North American Telecommunications Association |
| NATO | - | North Atlantic Treaty Organization |
| NAVSTAR | - | Navigational Satellite Timing |
| NBFM | - | narrow-band frequency modulation |
| NBH | - | network busy hour |
| NBRVF | - | narrowband radio voice frequency |
| NBS | - | National Bureau of Standards [now NIST] |
| NBSV | - | narrow-band secure voice |
| NC | - | Not Connected [pin], Normally Closed [switch] |
| NCA | - | National Command Authorities |
| NCC | - | National Coordinating Center for Telecommunications |
| NCS | - | National Communications System, net control station |
| NCSC | - | National Communications Security Committee |
| NDCS | - | network data control system |
| NDI | - | Non-developmental Item |
| NDER | - | National Defense Executive Reserve |
| NEACP | - | National Emergency Airborne Command Post |
| NEC | - | National Electric Code |
| NEP | - | noise equivalent power |
| NES | - | noise equivalent signal |
| NEXT | - | Near-End Crosstalk |
| NF | - | noise figure |
| NFPA | - | National Fire Protection Association |
| NFS | - | Network File System |
Next set of "N" Abbreviations and Acronyms
