• Commercial invoice
• Competitive intelligence
• Confidential information
• Continual improvement
• Corporate identity
• Customer intelligence, a discipline in marketing

Academia and education edit

• California State University, Channel Islands
• Channel Islands High School
• Collegium Invisibile
• Confucius Institute

Religion edit

• Josephites of Belgium, a Catholic congregation
• Christian Identity
• Christian Institute, a British charity which promotes Christian values

Other businesses and organizations edit

• Charity Intelligence Canada
• China Airlines (IATA code)
• Cigna health services (NYSE symbol)
• Consumers International
• Cycling Ireland
• CI Records, a music record label
• Cambria and Indiana Railroad
• CANZUK International, organisation which promotes cooperation between Canada, Australia, New Zealand and the United Kingdom
• Conservation International, an international environmental non-governmental organization
• Communications International, a former global union federation
• Communist International
• Children International, a non-profit child sponsorship organization

• Counterintelligence
• Confidential informant
• Compliance Inspection, a United States Air Force inspection
• Chief inspector, a police rank
• Circle inspector, a junior police rank
• Certificate of identity
• Civilian Internee, a special status of a prisoner during wartime
• Civilian Instructor, an adult volunteer in the British Air Training Corps

• Ci County, in Hebei, China
• Cayman Islands
• Chile (FIPS country code, obsolete NATO country code)
• Coney Island
• Cocos (Keeling) Islands, an external territory of Australia
• Cook Islands, an island-country in the South Pacific Ocean
• Côte d'Ivoire (ISO country code)
• Channel Islands
• Channel Islands of California
• Carbonia-Iglesias, a province in southern Italy
• Central India, region of India, abbreviated CI
  • Central India Circuit or C. I. Circuit, a Hindi film distribution circuit comprising parts of Madhya Pradesh (Indian state within central India)

Biology and medicine edit

• cI protein, a repressor protein of Enterobacteria phage λ
• Cytoplasmic incompatibility, a reproductive system
• Cardiac index
• Ci protein, Cubitus interruptus -protein
• Coital incontinence
• Convergence insufficiency
• Corpulence index
• Cumulative incidence, used as a measure of disease frequency in epidemiology
• Cochlear implant
• Chemical injury syndrome, an increased sensitivity to common chemicals also called multiple chemical sensitivity.
• Chronic illness, a condition that is long-lasting or recurrent
• Contraindication

Computing edit

• .ci, the Internet country code top-level domain (ccTLD) for Côte d'Ivoire
• Common Interface, for a Conditional Access Module
  • CI+, Common Interface Plus
• Computational intelligence
• Configuration item, the fundamental structural unit of a configuration management system
• Core Image, non-destructive image processing technology
• Continuous integration, a software-engineering practice of merging developer code into a main code base frequently
• CodeIgniter, a PHP framework

Earth science edit

• Cirrus cloud
• Convective instability

Mathematics edit

• Conditional independence, a type of relation of random variables in probability theory
• Confidence interval, an interval estimate of a population parameter used in statistics
• 101 (number) (in Roman numerals)
• Compound interest
• Cosine integral (standard mathematical symbols "Ci" and "ci")

Physics edit

• Conical intersection, the location of a discrete degeneracy between two electronic states
• Curie (unit) (Symbol: Ci), a measurement of radioactivity named after Marie Curie
• Copenhagen interpretation, an interpretation of quantum mechanics
• Cubic inch, a unit of volume

Other uses in science and technology edit

• CI group, a type of carbonaceous chondrite meteorite
• Carrier interferometry, a radio and optical communication coding technology
• Chemical ionization, a technique used in mass spectrometry
• Configuration interaction, a post-Hartree–Fock method used in computational chemistry
• Contextual inquiry, a user-centered design research method
• Collective intelligence, a subfield of sociology
• Colour Index International, a reference database of CI numbers for dyes and pigments
• Bavarian C I, a steam locomotive with the Royal Bavarian State Railways
• Compression ignition engine, another name for a diesel engine

• Canadian Idol, a Canadian television series
• Law & Order: Criminal Intent, an American television series
• Crime & Investigation Network
  • Crime & Investigation Network (Australia), Australian cable and satellite network focusing on Crime
  • Crime & Investigation Network (Europe), a pan-European television channel
  • Crime & Investigation Network (South East Asia)

• Ci (poetry), a form of Chinese lyric poetry
• Qi, a central concept in several eastern philosophies
• Categorical imperative, in philosophy
• Colour Index International, a reference database
• Comprehensible input
• Contact improvisation, a dance technique
• CI, postnominal for Companion of the Order of the Crown of India
• Ci, a form of the surname Qi, of the Tungusic peoples

• C1 (disambiguation)
• Cl (disambiguation)