| Cingulate cortex | Cingulate gyrus | CiNii |
| Cinnabar | Cinnamaldehyde | Cinnamic acid |
| Cinnamomum | Cinnamomum burmanni | Cinnamomum burmannii |
| Cinnamomum camphora | Cinnamomum cassia | Cinnamomum citriodorum |
| Cinnamomum glanduliferum | Cinnamomum loureiroi | Cinnamomum osmophloeum |
| Cinnamomum parthenoxylon | Cinnamomum pedunculatum | Cinnamomum tamala |
| Cinnamomum verum | Cinnamon | Cinnamon (software) |
| Cinnarizine | Cinnyricinclus leucogaster | Cinnyris asiaticus |
| Cinnyris habessinicus | Cinnyris osea | Cinnyris oseus/Nectarinia Osea |
| Cinnyris superbus | Cioteronel | Cipher |
| Ciphertext | Ciphertext-only attack | Cipières |
| Ciprian Deac | Ciprian Marica | Ciprian Tătărușanu |
| Ciprofibrate | Circaea lutetiana | Circaetus |
| Circaetus cinerascens | Circaetus cinereus | Circaetus fasciolatus |
| Circaetus gallicus | Circaetus pectoralis | Circassia |
| Circassian nationalism | Circassians | Circe |
| Circinae | Circle | Circle graph |
| Circle group | Circle of Willis | Circle Pines, Minnesota |
| Circle, Montana | Circleville, Kansas | Circleville, Ohio |
| Circleville, Utah | Circoviridae | Circuit breaker |
| Circuit court | Circuit de la Sarthe | Circuit de Nevers Magny-Cours |
| Circuit design | Circuit Park Zandvoort | Circuit Paul Ricard |
| Circuit reliability | Circuit switching | Circuit Switching |
| Circuit total limitation | Circuito de Jerez | Circuito del Jarama |
| Circular dichroism | Circular Dichroism | Circular motion |
| Circular orbit | Circular sector | Circular segment |
| Circular shift | Circulation (physiology) | Circulatory collapse |
| Circulatory system | Circumcision | Circumcision controversy in early Christianity |
| Circumcision of Jesus | Circumduction (anatomy) | Circumference |
| Circumfix | Circumpolar star | Circumscribed circle |
| Circus aeruginosus | Circus buffoni | Circus Charlie |
| Circus cinereus | Circus cyaneus | Circus macrourus |
| Circus maurus | Circus pygargus | Cirebon |
| Ciriaco de' Pizzicolli | Ciriaco Errasti | Ciriaco Sforza |
| Cirilo Antonio Rivarola | Ciro Capuano | Ciro Ferrara |
| Ciro Immobile | Cirrhosis | Cirripedia |
| Cirrus SR22 | Cirsium | Cirsium arvense |
| Cirsium creticum | Cirsium leucocephalum | Cirsium libanoticum |
| Cirsium syriacus | Cirsium texanum | Cirsium tuberosum |
| Cirsium turkestanicum | Cirsium vinaceum | Cirsium vulgare |
| Cirta | Cis | Cis-3-Hexen-1-ol |
| CISA | Cisalpine Republic | Cis–trans isomerism |
| Cisco ccna | Cisco Express Forwarding | Cisco IOS |
| Cisco Systems | Cisco, Illinois | Cisco, Texas |
| Cisgender | Cisne, Illinois | Cisplatin |
| Cisplatine War | Cissna Park, Illinois | Cissus |
| Cistaceae | Cistanche | Cistanche salsa |
| Cistanche tubulosa | Cisteae | Cistern |
| Cisterns of Tawila | Cisticola juncidis | Cistus |
| Cistus albidus | Cistus ×incanus | Cistus creticus |
| Cistus heterophyllus | Cistus incanus | Cistus ladanifer |
| Cistus libanotis | Cistus monspeliensis | Cistus populifolius |
| Cistus salviifolius | Cisuralian | Citadel |
| Citadel of Erbil | Citadel of the Hồ Dynasty | Citation |
| Cité de l'Architecture et du Patrimoine | Cité de l'espace | CITES |
| Citharexylum | Citharinus | Citi |
| Citibank | Citibank Morocco | Cities of Indonesia |
| Citipati | Citizen journalism | Citizen Kane |
| Citizen science | Citizendium | Citizendium.org |
| Citizenship | Citoyenneté romaine | Citrate |
| Citric acid | Citric acid cycle | Citrix Systems |
| Citroën | Citroën C4 | Citron |
| Citrullus | Citrullus colocynthis | Citrullus lanatus |
| Citrus | Citrus aurantiifolia | Citrus aurantium |
| Citrus × paradisi | Citrus ×aurantifolia | Citrus ×aurantium |
| Citrus ×bergamia | Citrus ×clementina | Citrus ×limon |
| Citrus ×paradisi | Citrus ×sinensis | Citrus ×tangerina |
| Citrus clementina | Citrus greening disease | Citrus japonica |
| Citrus limettioides | Citrus maxima | Citrus medica |
| Citrus medica var. sarcodactylis | Citrus production | Citrus psorosis virus |
| Citrus reticulata | Citrus reticulata × sinensis | Citrus tangerina |
| Citrus tristeza virus | Cittaslow | City |
| City bicycle | City block | City car |
| City Connection | City designated by government ordinance | City Football Group |
| City Hunter | City life (لعبة) | City Life (video game) |
| City Lights | City Manager | City marketing |
| City network | City of Arts and Sciences | City of Ember |
| City of God (2002 film) | City of Life | City of Life and Death |
| City of London | City of Manchester Stadium | City of the Dead (Cairo) |
| City Point, Wisconsin | City Protocol | City Slickers |
| City University London | City University of New York | City wiki |
| City Year | City-building game | City-state |
| Ciutat de Palma | Civetone | CIVETS |
| Civettictis civetta | Civic intelligence | Civic political culture |
| Civics | Civil and political rights | Civil authority |
| Civil aviation | Civil Aviation Administration of China | Civil Aviation Affairs |
| Civil Aviation and Meteorological Authority of Yemen | Civil Aviation Authority (United Kingdom) | Civil code |
| Civil discourse | Civil disobedience | Civil engineering |
| Civil Guard (Spain) | Civil law (legal system) | Civil liberties |
| Civil registry | Civil rights referendum | Civil society |
| Civil uprising phase of the Syrian Civil War | Civil war in Afghanistan (1989-1992) | Civil war in Afghanistan (1989–92) |
| Civil war in Afghanistan (1992-1996) | Civil war in Afghanistan (1992–96) | Civil war in Afghanistan (1996-2001) |
| Civil war in Afghanistan (1996–2001) | Civil war in Tajikistan | Civil-military operations |
| Civilian | Civilian control of the military | Civilisées |
| Civilization | Civilization (series) | Civilization V |
| Civilization V: Brave New World | Civilized core | Civitas Popthensis |
| Cizre | CJ Parker (wrestler) | CJCUC |
| CKM matrix | Cl | Claddagh ring |
| Cladding (construction) | Cladistics | Cladium mariscus |
| Cladobranchia | Cladocera | Cladorhynchus |
