| Curriculum Solutions Investigations | Academic & Science |
| College of Stupid Idiots | Academic & Science |
| Cardiological Society of India | Academic & Science |
| Computer Society of Iran | Academic & Science |
| انجمن کامپیوتر ایران | Academic & Science |
| انجمن كامپيوتر ايران | Academic & Science |
| Current Source Inverter | Academic & Science |
| Carbon Structural Integration | Academic & Science |
| Center for Student Involvement | Academic & Science |
| Cauchy Schwarz Inequality | Academic & Science |
| Conservation Science Investigations | Academic & Science |
| Conditional Symmetric Instability | Academic & Science |
| Construction Specifications Institute | Academic & Science |
| Capital Structure Irrelevance | Accounts and Finance |
| Computer Security Institute | Accounts and Finance |
| Casino | Airport Code |
| Colossus Minerals Incorporated (de-listed) | Business |
| Colorado Swimming Inc | Business |
| Commodity Systems Inc | Business |
| Collateral Services Incorporated | Business |
| Canadian Securities Institute | Business |
| Customer Satisfaction Indexing | Business |
| Cadsoft Solutions, Inc. | Business |
| Connectivity Services, Inc. | Business |
| Client Specific Instruction | Business |
| Creative Solutions Inc | Business |
| Confusing Set of Initials | Business |
| Colorado Structures Inc | Business |
| Caregiver Services Inc | Business |
| Cardiovascular Systems Inc | Business |
| Custom Staffing Inc | Business |
| Controls Southeast Inc | Business |
| Consulting Services Inc | Business |
| Contractors Society Insti | Business |
| Chase Industries, Inc. | Business |
| Computer Security International | Business |
| Cartwise Systems, Inc. | Business |
| Consultancy Sourcing and Implementation | Business |
| Coated Side In | Business |
| Campbell Scientific, Inc. | Business |
| Controlled Science Incorporated | Business |
| Customer Satisfaction Index | Business |
| Closure Systems International | Business |
| Concept Systems, Inc. | Business |
| Cooperative Services International | Business |
| Certified Success Instantly | Certifications |
| Certified Sucess Instantly | Certifications |
| Corporate Social Investment | Community |
| Christian Schools International | Community |
| Committee for Skeptical Inquiry | Community |
| ChildSafe International | Community |
| Crime Stoppers International | Community |
| Continuous School Improvement | Community |
| Christ Serving Individuals | Community |
| Cliftons Songwriter Initiative | Community |
| Catholic Scripture Intensive | Community |
| Cognitive Skills Index | Community |
| Current Swing Index | Community |
| Cultivating Significance and Influence | Community |
| Community Service Impact | Community |
| Community Security Initiative | Community |
| Community of Scholarly Innovation | Community |
| Community Service Infusion | Community |
| Center for School Improvement | Community |
| Conservation Science Initiative | Community |
| Club Sandwich Index | Community |
| Community Solutions Inc | Community |
| Compact Source Iodide | Community |
| Catholic Scouts of Ireland | Community |
| Combined Summer Institute | Community |
| Church Student Interaction | Community |
| Christ's Secret Investigators | Community |
| Church of South India | Community |
| Cool Science Investigations | Community |
| Construction Specification Institute | Computer and Networking |
| Computer Services Inc | Computing |
| CPU Support Identification | Computing |
| Computational Science Initiative | Computing |
| Custom Software Interface | Computing |
| Computers and Structures Inc | Computing |
| Convergence Sublayer Indication | Computing |
| Computer Science Index | Computing |
| Cyber Security Intelligence | Computing |
| Cyber Security Indonesia | Computing |
| Cyber Security Innovations | Computing |
| Cyber Security International | Computing |
| Cybersecurity Skills Index | Computing |
| Cyber Security Index | Computing |
| Cyber Security Institute | Computing |
| Cybersecurity Summer Institute | Computing |
| Client Side Include | Computing |
| Cisco Safe Implementation | Computing |
| Customer Support Identifier | Computing |
| Channel State Information | Computing |
| Command String Interface | Computing |
| Command Stream Interpreter | Computing |
| Corel Script Include | Computing |
| Control Sequence Introducer | Computing |
| Consolidated Software Inventory | Computing |
| Called Subscriber Identification | Computing |
| Computer Society of India | Computing |
| Clock Serial Interface | Computing |
| Common Synchronous Interface | Computing |
| Communications Side Information | Computing |
| Command Sequence Introducer | Computing |
| Compuserve Inc. | Computing |
| Complex Specified Information | Database Management |
| Criminal Science Investigation | Educational Degree |
| College Scene Investigation | Educational Institute |
| College of Staten Island | Educational Institute |
| College of Southern Idaho | Educational Institute |
| Critical Safety Item | General |
| California Solar Initiative | General |
| Cardio Strength Intervals | General |
| Chi Sigma Iota | General |
| Central States Indemnity | General |
| Consumer Survivor Initiative | General |
| Comprehension Strategies Instruction | General |
| Critical Solutions International | General |
| Catalysis Services International | General |
| Closure System International | General |
| Connect Serve And Impact | General |
| Criminally Stupid Individual | General |
| Corn Still Investigation | General |
| Comprehensive Swine Identification | General |
| Cruel Sadistic Idiot | General |
| Clovers Scientific Intelligence | General |
| Corpus Salesianum Italian | General |
| Commercial Systems Integrator | General |
| Car Seat Installation | General |
| Common Service Interface | General |
| Child Support Interactive | General |
| Creative Skills for Innovation | General |
| Continual Service Improvement | General |
| Container Storage Interface | General |
| Channel Status Information | General |
| Content Saturation Index | General |
| Cracklin Skin Investigators | General |
| Custom Satisfaction Information | General |
| Corporate Spending Innovations | General |
| Construction Specification Implementation | General |
| Customer Support ID | General |
| Commodity Selection Index | General |
| Companion of the Star of India | General |
| Cold Set Investigations | General |
| Camera Serial Interface | General |
| Customer Service Innovation | General |
| Common Sense Initiative | General |
| Collections Services Initiative | General |
| Combat Studies Institutetute | General |
| Centre for Social Innovation | General |
| Comprehensive Support and Improvement | General |
| Central Sophomore Initiative | General |
| Collect Semen Immediately | General |
| Classic Slip Inversion | General |
| Cold Start Injector | General |
| Compression Sense Ignition | General |
| Coupe Sport Injection | General |
| Customer Service Index | General |
| Corvettes of Southeast Idaho | General |
| Compression and Spark Ignition | General |
| Chevrolet Spin Indonesia | General |
| Child Safety Initiative | General |
| Club Subaru Impreza | General |
| Component Servicing Infrastructure | General |
| Club Seat Ibiza | General |
| Child Seat Isofix | General |
| Catalytic Solutions Inc. | General |
| Club Saga Iswara | General |
| Club Sport Injected | General |
| Club Sport Intelligent | General |
| Comfort Super Injection | General |
| Civic Si | General |
| Counter Strike Incorporated | General |
| Customer Supplies Income | General |
| Consumer Safety Inspector | Governmental |
| Cemetery Scene Investigation | Governmental |
| Community Service Initiative | Governmental |
| Crime Scene Investigator | Governmental |
| Crash Scene Investigator | Governmental |
| Center Station In charge | Governmental |
| Committee Of Suansation Institution | Governmental |
| Crime Scene Investigations | Governmental |
| Canadian Softwood Inspection | Governmental |
| Charter School Institute | Governmental |
| Crime Scene Investigators | Governmental |
| Cadet Sub Inspector | Governmental |
| Civic Service Institute | Governmental |
| Center for the Study of Intelligence | Governmental |
| California Specifications Index | Governmental |
| Coupe Sport Injected | Governmental |
| Crime Scene Investigation | Governmental |
| Common System Interface | Information Technology |
| Color Solutions International | International |
| Colourist Society International | International |
| Childbirth Survival International | International |
| Colorist Society International | International |
| Cetacean Society International | International |
| Confederación de Sindicatos Independientes | International |
| Conferencia Socialista Ibérica | International |
| Corporación de la Siderúrgica Integral | International |
| Corriente Sindical de Izquierdas | International |
| Can't Stand Idiots | Internet |
| Can't Speak Italian | Internet |
| Can't Stand It | Internet |
| Criminal Science Investigator | Jobs |
| Cosmetic Surgery Incorporated | Medical |
| Control Sequence Introduction | Medical |
| Clinical Scene Investigator | Medical |
| Crash Scene Investigation | Medical |
| Cookies Sound Interesting | Messaging |
| Critical Satellite Image | Military and Defence |
| Critical Sustainability Item | Military and Defence |
| Combat Studies Institute | Military and Defence |
| Container Security Initiative | Military and Defence |
| Chinese System Interface | Networking |
| Contact Surface Imaging | Physics Related |
| Central States Industrial | Regional |
| Casino, New South Wales, Australia | Regional |
| Collateral Services Inc. | Softwares |
| Co-elliptic Sequence Initiation | Space Science |
| Control Servo Input | Space Science |
| Controls-structures Interaction | Space Science |
| Common Software Interface | Space Science |
| Control Sequence Indicator | Space Science |
| Commission Sportive Internationale | Sports |
| Cape Sailing Institute | Sports |
