| Acronym | Definition |
|---|
| OPERA | Oscillation Project with Emulsion-Tracking Apparatus (Geneva, Switzerland) |
| OPERA | Open PLC European Research Alliance |
| OPERA | Optical Packet Experimental Routing Architecture (lightwave technology) |
| OPERA | Operational Programme for the Exchange of Weather Radar Information (EUMETNET) |
| OPERA | Offers and Prospectuses Electronic Repository and Access (Singapore) |
| OPERA | Out-Performance Equity Redeemable in Any Asset (convertible bond) |
| OPERA | Organised Programme of Experimentation and Research into ATM |
| OPERA | On-Line Periodicals and Research Area (IEEE) |
| OPERA | Officer Professional Effectiveness Review for the Army (Australian Army) |
| OPERA | Office of Program Evaluation & Risk Analysis |
| OPERA | Outpatient Endometrial Resection and Ablation (medical procedure) |
| OPERA | Opinion, Perspective, Expertise, Research, Analysis |
| OPERA | Observatoire Permanent de la Radioactivité dans l'Environnement (French: Permanent Observatory of Radioactivity in the Environment) |