| Acronym | Definition |
|---|
| CIAO | Columbia International Affairs Online |
| CIAO | Critical Infrastructure Assurance Office |
| CIAO | Component-Integrated ACE ORB |
| CIAO | Chandra Interactive Analysis of Observations |
| CIAO | Certified Illinois Assessing Officer (property assessments) |
| CIAO | Cultural Italian American Organization |
| CIAO | Clinical Information Access Online |
| CIAO | Chief Infrastructure Assurance Officer (US FEMA) |
| CIAO | Coronagraphic Imager with Adaptive Optics (National Astronomical Observatory of Japan) |
| CIAO | Centro Informazioni Accoglienza Orientamento (Italy) |
| CIAO | CLAM-INKA-OMRS |
| CIAO | Centre for Informatics and Applied Optimization (University of Ballarat, Australia) |
| CIAO | Charitable Italian American Organization (Ohio) |
| CIAO | Carleton in and Out (Carleton College queer centered group) |
| CIAO | CiAO Is Aspect-Oriented |
| CIAO | Centre d'Information Jeunesse Assisté par Ordinateur (French: Computer Aided Youth Information Center; Switzerland) |
| CIAO | Council on International and Area Outreach (University of Tennessee) |
| CIAO | Commodity Import Analysis & Operation (USDA) |
| CIAO | Canadian Italian Appreciation Organization (Canada) |