| Acronym | Definition |
|---|
| IIA | Institute of Internal Auditors |
| IIA | Internet Industry Association (Australia) |
| IIA | Indianapolis International Airport (Indianapolis, IN) |
| IIA | Illinois Institute of Art (Chicago, IL) |
| IIA | International Institute of Anthropology (Salt Lake City, UT) |
| IIA | Industria Italiana Autobus (Italian: Italian Industry Bus) |
| IIA | Insurance Institute of America |
| IIA | Information Industry Association |
| IIA | Independence of Irrelevant Alternatives (decision theory axiom) |
| IIA | Inform and Influence Activities (US Army) |
| IIA | Investment Intermediaries Act (Ireland) |
| IIA | Indian Institute of Architects |
| IIA | Istituto sull'Inquinamento Atmosferico (Italian: Institute for Atmospheric Pollution) |
| IIA | Information International Associates, Inc |
| IIA | Individual Investigator Agreement |
| IIA | International Irradiation Association |
| IIA | International Investment Agreement (multi-country agreement) |
| IIA | Improved Immune Algorithm |
| IIA | Inchon International Airport |
| IIA | Iwaki International Association (Japan) |
| IIA | Ideas In Action |
| IIA | Iwate International Association (Japan) |
| IIA | International Internet Association |
| IIA | International Institute of Agriculture |
| IIA | Istituto Italo-Africano |
| IIA | Information Interchange Architecture |
| IIA | Incinerator Institute of America |
| IIA | Integrated Investment Analysis |
| IIA | Instrument Interface Agreement |
| IIA | If Incorrect, Advise |
| IIA | International ISBN (International Standard Book Number) Agency (publishing) |
| IIA | Individual Issue Ammunition |
| IIA | International Investment Advisors, LLC |
| IIA | Installation Information Architecture |