CI

CI or Ci may refer to:

Business terminology[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

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)

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

.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

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")

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

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