| Acronym | Definition |
|---|
| ECO | Engineering Change Order |
| ECO | Electronic Central Office |
| ECO | Ecology |
| ECO | Economics |
| ECO | Engineering, Construction & Operations |
| ECO | Economic Cooperation Organization |
| ECO | Environmental Careers Organization |
| ECO | Electronic Control (Sprint) |
| Eco | Escherichia Coli |
| ECO | Early Childhood Outcomes |
| ECO | Environmental Career Opportunities |
| ECO | Ethernet Connection (NEC) |
| ECO | Earls Court and Olympia (London, England) |
| ECO | European Cluster Observatory (regional economic information) |
| ECO | Environmental Conservation Organization |
| ECO | Early Canadiana Online (digital library) |
| ECO | Environmental Commissioner of Ontario (Canada) |
| ECO | Execution and Control of Operations |
| ECO | Engine Certification Office (FAA) |
| ECO | Entry Clearance Officer (UK immigration) |
| ECO | Encyclopedia of Chess Openings |
| ECO | Edison-Chouest Offshore |
| ECO | Emergency Custody Order (mental health) |
| ECO | Environmental and Conservation Organisations (of Aotearoa, New Zealand) |
| ECO | Enterprise Core Object |
| ECO | Electron-Coupled Oscillator |
| ECO | Energy Cut Off |
| ECO | Ecological Scenario |
| ECO | Emergency Coordinating Officer |
| ECO | Equity Carve-Out |
| ECO | Entry Control Officer (UK fire service) |
| ECO | Earth Communication Office |
| ECO | Electronic Countermeasures Officer |
| ECO | European Communications Office |
| ECO | Equipment Control Officer |
| ECO | Emergency Changeover Order signal (CCS #7 & ITU-T) |
| ECO | Export Control Organization (UK) |
| ECO | electronic combat officer (US DoD) |
| ECO | Enhanced Connectivity Options (AT&T) |
| ECO | European Certifying Organization SpA (Italy) |
| ECO | Economic Competitive Opportunity |
| ECO | Electioneering Communication Organizations |
| ECO | Emergency Control Officer |
| ECO | Environmental Citizen Organisation |
| ECO | End Central Office (NARTE) |
| ECO | Embarkation Control Office |
| ECO | Edit Change Order |
| ECO | Engagement Control Officer (Tomahawk) |
| ECO | Experiment in Construction with Object-Oriented Methods |
| ECO | Extraordinary Customer Opportunity (Sprint) |
| ECO | Elite Combat Operatives (gaming clan) |
| ECO | Equal Competitive Opportunity (FCC) |
| ECO | Environmental Compliance Organization International LLC (Portland, OR) |
| ECO | Education and Communication Officer (UK) |
| ECO | Equitable Consideration Offer (IRS) |
| ECO | Emil Chronicle Online (role-playing game) |
| ECO | Enhanced Company Operations (US Marine Corps) |
| ECO | Executive Council Office (Canada) |