| Computer Information Systems | Academic |
| Current Index to Statistics | Academic & Science |
| Center for Imaging Science | Academic & Science |
| Computational Intelligence Society | Academic & Science |
| Clinical Immunology Society | Academic & Science |
| Council of International Schools | Academic & Science |
| China Instrument and Control Society | Academic & Science |
| 中国仪器仪表学会 | Academic & Science |
| Zhōngguó Yíqì Yíbiǎo Xuéhuì | Academic & Science |
| Chemical Inventory System | Academic & Science |
| Campus International School | Academic & Science |
| Chinese International School | Academic & Science |
| Copenhagen International School | Academic & Science |
| Colombo International School | Academic & Science |
| Canadian Interuniversity Sport | Academic & Science |
| Computer and Information Science | Academic & Science |
| Constant Injection System | Academic & Science |
| Comprehensive Income Statement | Accounts and Finance |
| Canton Island | Airport Code |
| Centre for Independent Studies | Associations & Organizations |
| Commonwealth of Independent States | Banking |
| Corporate Identity System | Business |
| Certified Incentive Specialist | Business |
| Computer Integrated Services | Business |
| Certified IPC Specialist | Business |
| Computerized Information System | Business |
| Co-operative Insurance Society | Business |
| Chemical Information Systems, Inc. | Business |
| Client Information System | Business |
| Communication Information Systems | Business |
| Continuous Ink System | Business |
| Construction Industry Scheme | Business |
| Chase Information Systems | Business |
| Collaborative Information System | Business |
| Common Information System | Business |
| Com Internet Services | Business |
| Chemical Information System | Chemistry |
| Continuous Interleaved Sampling | Chemistry |
| Carbonlite Ionet Suspension | Chemistry |
| Cuba Independent Schools | Community |
| Church in Society | Community |
| Centrum voor Israëlstudies | Community |
| Casualty Information Society | Community |
| Communities In the Schools | Community |
| Community Investment Strategy | Community |
| Commission on Independent Schools | Community |
| Cities In Schools | Community |
| Communities in Schools | Community |
| Center for Immigration Studies | Community |
| Community Information System | Community |
| Character Information Sheet | Community |
| Communicating In Spanish | Community |
| Combat In School | Community |
| Christians In Science | Community |
| Cut It Short | Computing |
| Computer and Information Systems | Computing |
| Computing and Information Science | Computing |
| Commercial Instruction Set | Computing |
| Card Information Services | Computing |
| Credit Information System | Computing |
| Computational Intelligence and Security | Computing |
| Cybersecurity Intelligence System | Computing |
| Configuration Items | Computing |
| Cyber Infrastructure | Computing |
| Computer Information Science | Computing |
| Common Internet Services | Computing |
| Commercial Internet Service | Computing |
| Card Information Structure | Computing |
| Customer Intercept Service | Computing |
| Commercial Internet System | Computing |
| Case Integration Services | Computing |
| Content Identification System | Computing |
| Computer Information System | Computing |
| Context Information Store | Computing |
| Collaborations in Internet Security | Computing |
| Cooperative Information Systems | Computing |
| Customer Interaction Software | Computing |
| Center for Internet and Society | Computing |
| Computer Interface Station | Computing |
| Content Immutable Storage | Computing |
| Computer Informations Systems | Computing |
| Conversion Indexing Sorting | Computing |
| Computer Information Services | Computing |
| Central Independent States | Country Specific |
| Continuous Injection System | Earth Science |
| Copper Indium Diselenide | Electronics |
| Center for Integrative Studies | General |
| Compliance Implementation Services | General |
| Children's Integrated Services | General |
| Center For Integrated Systems | General |
| Crew Information Systems | General |
| Cabin Interphone System | General |
| Checklist Individual Strength | General |
| Center for International Studies | General |
| Cosine I Sine | General |
| Confederation of Independent States | General |
| Compass Information System | General |
| Central Index System | General |
| Information Services | General |
| Credentialing Information System | General |
| Certified IPC (Institute of Printed Circuits) Specialist | General |
| Centro de Intercambio y Solidaridad | General |
| Citrix Insight Services | General |
| Corporate Individual Scheme | General |
| Citizen Information Service | General |
| Communication and Information Systems | General |
| Center for Industrial Services | General |
| Conflict Intervention Service | General |
| Cooperative Interstate Shipment | General |
| Center of Interchange and Solidarity | General |
| Cisgender | General |
| Campaign Information System | General |
| Crash Injury Study | General |
| Car Immobilizer System | General |
| Car Information System | General |
| Constant Idle Speed | General |
| Curb Idle Speed | General |
| Clutch Interlock Switch | General |
| Contrast Interior Scheme | General |
| Crusade Information Sheets | General |
| Compressed Image Similar | General |
| Cheated In Silverware | General |
| Cruising In Style | General |
| Configuration Interaction Single | General |
| Corpus Inscriptionum Swissnet | General |
| A Country Of Independent Societies | General |
| Cairngorm Information System | General |
| Cynical Information System | General |
| Compressor Inlet Sensor | General |
| Clark International Speedway | General |
| Campionato Italiano Superturismo | General |
| Classic Infotainment System | General |
| Cytokine Inducible Stke | General |
| Culligan Information Systems | General |
| Commonwealth Of Independant States | General |
| A Coordinating Instructional Staff | General |
| Counterterrorism Intelligence Service | General |
| Continuous Inking Some | General |
| Confederacy of Independent Systems | General |
| Corporate Information System | General |
| Certified Instrument Specialist | General |
| Citizenship and Immigration Services | Governmental |
| Corruption is Systemic | Governmental |
| Citizenship Immigration Services | Governmental |
| Contractor's Information Submittal | Governmental |
| Capital Investment Strategy | Governmental |
| Cancer Information Service | Governmental |
| Catastrophic Incident Supplement | Governmental |
| Cabrini Immigrant Services | Governmental |
| Community Innovation Surveys | Governmental |
| Commemorative Integrity Statement | Governmental |
| Consumer Information Statement | Governmental |
| Court Information System | Governmental |
| Chinese International Shipping | Governmental |
| Cargo Information Service | Governmental |
| Central Intelligence Services | Governmental |
| Colonial Intelligence Service | Governmental |
| Criminal Investigation Section | Governmental |
| Customs Information System | Governmental |
| Constant Idle System | Governmental |
| Criminally Insane Snipers | Governmental |
| Committee for Internal Security | Governmental |
| Cockpit Instrumentation System | Governmental |
| Case Information Study | Governmental |
| Criminal Information System | Governmental |
| Commercial Insurance Services | Insurance |
| Centro de Investigaciones Sociológicas | International |
| Corpus Inscriptionum Semiticarum | International |
| Computer Internet System | Internet |
| Career Information System | Jobs |
| Clinically Isolated Syndrome | Medical |
| Carcinoma In Situ | Medical |
| Care Information System | Medical |
| Catheter-Induced Spasm | Medical |
| Central Inhibitory State | Medical |
| Central Issue System | Medical |
| Chromosome Information System | Medical |
| Computerised Information System | Medical |
| Coronary Intervention Study | Medical |
| Cytokine-Inducing Substance | Medical |
| Computer Integrated Surgery | Medical |
| Clinical Information System | Medical |
| Chromosome Insertion Sequence | Medical |
| Can It Sam | Messaging |
| Criminal Investigative Service | Military and Defence |
| Combat Identification System | Military and Defence |
| Critical Information Shortfall | Military and Defence |
| Communications Interface Shelter | Military and Defence |
| Common Item Support | Military and Defence |
| Contact Image Sensor | Military and Defence |
| Command Information System | Military and Defence |
| Component Information System | Military and Defence |
| Confederation of Independent Systems | Networking |
| Compuserve Information Service | Networking |
| Computer Internet Server | Networking |
| Centre for Intergroup Studies | Regional |
| Composite Information Server | Softwares |
| Center for Internet Security | Space Science |
| Central Integration Site | Space Science |
| Change Impact Summary | Space Science |
| Communication Interface System | Space Science |
| Component Identification Sheet | Space Science |
| Customer Information System | Space Science |
| Candian Interuniversity Sport | Sports |
| Chartered Institute of Stockbrokers | Stock Exchange |
| Contact Image Sensing | Technology |
| Canton Island Airport | Transport & Travel |
