| Community Of Science | Academic & Science |
| Cluster of Students | Academic & Science |
| Société Canadienne d'Ophtalmologie | Academic & Science |
| Cooper Ornithological Society | Academic & Science |
| Center for Open Science | Academic & Science |
| College of the Siskiyous | Academic & Science |
| College Of Science | Academic & Science |
| Centre for Omic Sciences | Academic & Science |
| CO-Operative Society | Business |
| Cost Of Sale | Business |
| Coordination Of Supply | Business |
| Canadian Oil Sands Trust | Business |
| Certified Occupancy Specialist | Certifications |
| Church Of the Shepherd | Community |
| Community Optional Service | Community |
| Church Of Scientology | Community |
| Church Of Satan | Community |
| Christ Our Savior | Community |
| Christian Outreach Service | Community |
| Company Of Song | Community |
| Counselors Only Section | Community |
| Corporation Of Seniors | Community |
| Corporation for Open Systems | Computer and Networking |
| Consumer Off the Shelf | Computing |
| Corporation of Open Systems | Computing |
| Custom Operating System | Computing |
| Conqueror Of Shamballa | Computing |
| Control System | Computing |
| Crypto Operating System | Computing |
| Cray Operating System | Computing |
| Corba Object Services | Computing |
| Common Operations Services | Computing |
| Configuration Object Set | Computing |
| Central Offices | Computing |
| Certificate Of Service | Computing |
| Card Operating System | Computing |
| Cassette Operating System | Computing |
| Clip On Socket | Computing |
| Commercial Operating System | Computing |
| Call Originate Status | Computing |
| Console Operating System | Computing |
| Cloud Operating System | Computing |
| Compatibility Operating System | Computing |
| Contentos | Cryptocurrency |
| College of Sciences | Educational Institute |
| College of The Sequoias | Educational Institute |
| Consequence of Sound | General |
| Collection of Style | General |
| Circle of Steel | General |
| Cost Of Sales | General |
| Copy Other System | General |
| Corrected On Site | General |
| Carlisle Operating System | General |
| Connoisseur Of Sound | General |
| Child Outcomes Summary | General |
| Cult Of Spike | General |
| Cracco Outerspace Special | General |
| Center for Offshore Safety | General |
| Child Outcome Summary | General |
| Carousel Object System | General |
| China Operating System | General |
| City Of Saskatoon | General |
| Contest Of Speed | General |
| Carrier Operated Switch | General |
| Cloud Object Storage | General |
| Cut Offs Scraps | General |
| Clear of Seal Position | General |
| Coil Over Suspension | General |
| Coil Over Shock | General |
| Colorado Springs Design Center | General |
| Central Ohio Subarus | General |
| Caravan Of Stars | General |
| Continental Signature | General |
| Completion Of Steer | General |
| Content Optimization System | General |
| City of Colorado Springs Municipal Airport | Governmental |
| Chief Operations Specialist | Governmental |
| Certificate Of Sponsorship | Governmental |
| City Of Stirling | Governmental |
| Criminal Organization System | Governmental |
| Council Of Specialties | Governmental |
| Central Office Special | Governmental |
| Chief Of Station | Governmental |
| Certificate of Suitability | Governmental |
| COSmetic registration number | Governmental |
| Coordinadora de Organizaciones Sindicales | International |
| Co-sine (Kosinüs) | International |
| Check On Site | Internet |
| Confirm On Site | Internet |
| Chief of Security | Jobs |
| Computer Operations Specialist | Jobs |
| Canadian Oncology Society | Medical |
| Canadian Ophthalmological Society | Medical |
| Change of Subject | Messaging |
| Critical Operational Specialties | Military and Defence |
| Corps Support | Military and Defence |
| Communications Segment | Military and Defence |
| Civilian Occupational Specialty | Military and Defence |
| Contingency Operating Station | Military and Defence |
| Covert Organization Search | Military and Defence |
| Champions of The Sea | Military and Defence |
| Chief of Supply | Military and Defence |
| Company Orderly Sergeant | Military and Defence |
| Critical Occupational Specialty | Military and Defence |
| Class of Service | Networking |
| Common Object Services | Networking |
| Central Operating System | Networking |
| Cost of Service | Networking |
| Change of State | Physics Related |
| Certificate of Occupancy | Real Estate |
| City of Colorado Springs Municipal Airport, Colorado Springs, Colorado USA | Regional |
| Canadian Oil Sands | Regional |
| Collaborative Operating System | Softwares |
| Computer Operating System | Softwares |
| Comet Operating System | Softwares |
| Corba Object Service | Softwares |
| Carousel Object Store | Softwares |
| Cosmic Origins Spectrograph | Space Science |
| Carry-on Oxygen System | Space Science |
| Control Operating System | Space Science |
| Co-orbiting Satellite | Space Science |
| Cosine | Space Science |
| Chamber of Secrets | Sports |