| Abbreviation | Definition |
|---|---|
| NISD | Northside Independent School District |
| NISDA | Nantucket Island School of Design the Arts |
| NISDA | National Independents Schools Drama Association |
| NISS | Nacel International School System |
| NISS | Nexus International School Singapore |
| NISS | North Island Secondary School |
| NIST | New International School of Thailand |
| NJH | North Junior High School |
| NJHS | National Junior Honors Society |
| NJHS | New Jewish High School |
| NJIS | North Jakarta Intercultural School |
| NJJS | New Jersey Japanese School |
| NJMS | Nativity Jesuit Middle School |
| NJMS | New Jersey Medical School |
| NJMS | North Johnston Middle School |
| NJROTC | Navy Junior Reserve Officers Training Corps |
| NKCSD | North Kansas City School District |
| NKHS | New Kent High School |
| NKHS | North Kingstown High School |
| NKHS | North Knox High School |