| Cyclines | Cyclin |
| cyclique | recurrent |
| cycliser | cyclize |
| cyclisme | cycling |
| Cyclisme artistique | Artistic cycling |
| Cyclisme aux Jeux Olympiques | Cycling at the Summer Olympics |
| Cyclisme de descente | Downhill cycling |
| Cyclisme handisport | Handcycle |
| cyclisme sur piste | track cycling |
| Cyclisme sur route | Road bicycle racing |
| Cyclisme urbain | Utility cycling |
| cycliste | biker |
| cyclo- | cyclo- |
| Cyclo-cross | Cyclo-cross |
| cycloalcane | cycloalkane |
| cyclobutane | cyclobutane |
| Cycloconvertisseur | Cycloconverter |
| Cyclogénèse | Extratropical cyclone |
| Cyclogénèse tropicale | Tropical cyclogenesis |
| cycloheptane | cycloheptane |
| cyclohexane | cyclohexane |
| Cycloheximide | Cycloheximide |
| Cyclomessager | Bicycle messenger |
| cyclomoteur | autocycle |
| cyclonal | cyclonic |
| cyclone | hurricane |
| Cyclone Catarina | Cyclone Catarina |
| Cyclone extratropical | Extratropical cyclone |
| Cyclone Gonu | Cyclone Gonu |
| Cyclone polaire | Polar cyclone |
| Cyclone Sidr | Cyclone Sidr |
| Cyclone tropicadal | Tropical cyclone |
| Cyclone tropical | Tropical cyclone |
| Cyclones de Cincinnati | Cincinnati Cyclones |
| cyclonique | cyclonic |
| cyclope | cyclops |
| cyclopentane | cyclopentane |
| Cyclophyllidea | Cyclophyllidea |
| Cyclopoida | Cyclopoida |
| cyclopropane | cyclopropane |
| Cyclops | Cyclops |
| Cyclorana | Cyclorana |
| Cyclorana alboguttata | Striped Burrowing Frog |
| Cyclorana platycephala | Cyclorana platycephala |
| Cyclorrhapha | Cyclorrhapha |
| cyclostome | cyclostome |
| Cyclotourisme | Bicycle touring |
| cyclotouriste | biker |
| cyclotron | cyclotron |
| cycloïde | cycloid |
| Cycnos | Cycnus |
| Cydippe | Cydippe |
| Cydnidae | Cydnidae |
| Cydonia Mensae | Cydonia Mensae |
| cygne | swan |
| cygne chanteur | whooper swan |
| cygne femelle | swan |
| cygne mâle | swan |
| cygne noir | black swan |
| cygne siffleur | Bewick's swan |
| cygne trompette | trumpeter swan |
| Cygne tuberculé | Mute Swan |
