CSO
Abbreviation with 6 meanings
| Stands for | Combined sewer overflow |
|---|---|
| Meanings | 6 |
| Categories | Science & Engineering, Business & Finance, Military, Organizations & Companies |
CSO has six meanings. The most common are Combined sewer overflow (environmental) and Chief security officer (job title); it can also stand for Chief strategy officer, Chief sustainability officer, Chief of Space Operations and Civil society organization.
Meanings of CSO at a glance
| # | CSO stands for | Context |
|---|---|---|
| 1 | Combined sewer overflow | Science & Engineering › Environmental |
| 2 | Chief security officer | Business & Finance › Job Title |
| 3 | Chief strategy officer | Business & Finance › Job Title |
| 4 | Chief sustainability officer | Business & Finance › Job Title |
| 5 | Chief of Space Operations | Military › Military Unit and Organization |
| 6 | Civil society organization | Organizations & Companies › Nonprofit |
1. Combined sewer overflow
Science & Engineering · Environmental Abbreviations
Discharge of untreated sewage mixed with stormwater from older sewer systems that carry both in the same pipes. During heavy rain these systems exceed their capacity and overflow into rivers, lakes or the sea through designated outfalls.
Example: Swimming is not advised for 48 hours after heavy rain because of CSO discharges into the harbor.
About 700 US communities, mostly older cities in the Northeast and Great Lakes, have combined sewers. London's Thames Tideway Tunnel, a 25-kilometer "super sewer" built in the 2010s and 2020s, was designed to capture overflows. Paris spent heavily to reduce CSOs so the Seine could host swimming events at the 2024 Olympics.
2. Chief security officer
Business & Finance · Job Title Abbreviations
Oversees an organization's overall security, which can include physical protection of people and facilities, corporate investigations and, in many firms, cybersecurity. Where a separate CISO exists, the CSO may concentrate on physical and enterprise security.
Example: After the threats against staff, the CSO added guards and badge readers at every office.
The split between CSO and CISO is not standardized: technology companies often use CSO for their top cybersecurity executive. Banks, casinos and utilities typically give the CSO strong physical-security responsibilities.
3. Chief strategy officer
Business & Finance · Job Title Abbreviations
Executive who helps the CEO set and carry out corporate strategy, leading strategic planning, market analysis, portfolio decisions and often mergers and acquisitions or transformation programs. Many come from management consulting backgrounds.
Example: The CSO is running a review of which business lines to keep, grow or sell.
The role varies widely: some CSOs run small planning teams, while others oversee corporate development and major initiatives. CSO also commonly abbreviates chief security officer and chief sustainability officer, and in Ireland it is the Central Statistics Office.
4. Chief sustainability officer
Business & Finance · Job Title Abbreviations
Executive who leads environmental and social sustainability strategy, including emissions targets, climate risk, supply-chain practices and ESG reporting. The role has expanded as investors and regulators demand climate and sustainability disclosures.
Example: The CSO committed the company to net-zero emissions across its supply chain by 2040.
DuPont is often cited as one of the first companies to create the role, in 2004. EU rules such as the Corporate Sustainability Reporting Directive (CSRD) increased the workload and visibility of CSOs. Some companies place the role within finance because sustainability data now feeds regulated reports.
5. Chief of Space Operations
Military · Military Unit and Organization Abbreviations
Professional head of the US Space Force, a four-star general who leads the service and sits on the Joint Chiefs of Staff. The title echoes the Navy's chief of naval operations rather than the Air Force's chief of staff.
Example: The CSO said the Space Force needs more satellites that can maneuver to avoid threats.
Gen. John W. "Jay" Raymond became the first CSO when the Space Force was created in December 2019. In business CSO means chief security officer or chief strategy officer, and in public health it can mean combined sewer overflow.
6. Civil society organization
Organizations & Companies · Nonprofit Abbreviations
Broad term for any organization outside government and business that represents citizens' interests, including NGOs, charities, trade unions, faith groups, professional associations and community groups.
Example: CSOs submitted joint recommendations to the review panel.
International bodies such as the UN, World Bank and EU use CSO as a more inclusive term than NGO. Civil society is often described as the "third sector" between state and market. In corporate titles, CSO can mean chief security officer, chief strategy officer or chief sustainability officer.
Related abbreviations
More environmental abbreviations
- CO2e – Carbon dioxide equivalent
- COD – Chemical oxygen demand
- COP – Conference of the Parties
- CR – Critically Endangered
- DAC – Direct air capture
- DO – Dissolved oxygen
- EIA – Environmental impact assessment
- EIS – Environmental impact statement
See all 62 environmental abbreviations →