| Acronym | Definition |
|---|
| NIA | National Institute on Aging (US NIH; also seen as NIOA) |
| NIA | National Indoor Arena (UK) |
| NIA | National Insulation Association |
| NIA | National Intelligence Agency (South Africa and Thailand) |
| NIA | National Institute of Accountants |
| NIA | National Irrigation Administration (Philippines) |
| NIA | Neuromuscular Integrative Action (mind-body-spirit fitness technique) |
| NIA | National Institute of Aerospace |
| NIA | National Insulator Association |
| NIA | Nuclear Industry Association (UK) |
| NIA | Net Internal Area (internal building space) |
| NIA | No Information Available |
| NIA | Net Income Attributable |
| NIA | New Iraqi Army |
| NIA | Nigerian Institute of Architects (est. 1960) |
| NIA | Network Interface Adapter |
| NIA | Newcastle International Airport (England; also see NCL) |
| NIA | New Indo-Aryan (linguistics) |
| NIA | National Infantry Association |
| NIA | Northern and Isolation Allowance (Canadian physician incentive) |
| NIA | Nature in Art (UK museum) |
| NIA | Network Infrastructure Administration |
| NIA | Nursing Informatics Australia (Health Informatics Society of Australia) |
| NIA | Nearest International Airport |
| NIA | Network Indicate Address |
| NIA | Non-Instructed Advocacy |
| NIA | Nails Industry Association |
| NIA | Number Of Imposter Attempts (biometrics) |
| NIA | National Information Accounts Clearinghouse |
| NIA | Navy Industrial Association |
| NIA | Neoplasia Intra-Epitelial Anal (Portugese) |
| NIA | National Information Account |
| NIA | Nerd Intelligence Agency |
| NIA | Naval Intelligence Assessment |
| NIA | National Information Association |
| NIA | National Investigation Agency (India) |
| NIA | Not in Attendance (school) |
| NIA | National Insurance Act (various locations) |
| NIA | Neural Impulse Actuator (brain-computer interface) |
| NIA | Noobs in Action (gaming) |