CI

CI or Ci may refer to:

Business terminology

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 protein, a repressor protein of Enterobacteria phage λ
Cytoplasmic incompatibility, a reproductive system
Cardiac index
Ci protein, Cubitus interruptus -protein
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 (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