| conversant | Thoroughly informed. |
| conversion | Change from one state or position to another, or from one form to another. |
| convertible | Interchangeable. |
| convex | Curving like the segment of the globe or of the surface of a circle. |
| conveyance | That by which anything is transported. |
| convivial | Devoted to feasting, or to good-fellowship in eating or drinking. |
| convolution | A winding motion. |
| convolve | To move with a circling or winding motion. |
| convoy | A protecting force accompanying property in course of transportation. |
| convulse | To cause spasms in. |
| convulsion | A violent and abnormal muscular contraction of the body. |
| copious | Plenteous. |
| coquette | A flirt. |
| cornice | An ornamental molding running round the walls of a room close to the ceiling. |
| cornucopia | The horn of plenty, symbolizing peace and prosperity. |
| corollary | A proposition following so obviously from another that it requires little demonstration. |
| coronation | The act or ceremony of crowning a monarch. |
| coronet | Inferior crown denoting, according to its form, various degrees of noble rank less than sovereign. |
| corporal | Belonging or relating to the body as opposed to the mind. |
| corporate | Belonging to a corporation. |
| corporeal | Of a material nature; physical. |
| corps | A number or body of persons in some way associated or acting together. |
| corpse | A dead body. |
| corpulent | Obese. |
| corpuscle | A minute particle of matter. |
| correlate | To put in some relation of connection or correspondence. |
| correlative | Mutually involving or implying one another. |
| corrigible | Capable of reformation. |
| corroborate | To strengthen, as proof or conviction. |
| corroboration | Confirmation. |
| corrode | To ruin or destroy little by little. |
| corrosion | Gradual decay by crumbling or surface disintegration. |
| corrosive | That which causes gradual decay by crumbling or surface disintegration. |
| corruptible | Open to bribery. |
| corruption | Loss of purity or integrity. |
| cosmetic | Pertaining to the art of beautifying, especially the complexion. |
| cosmic | Pertaining to the universe. |
| cosmogony | A doctrine of creation or of the origin of the universe. |
| cosmography | The science that describes the universe, including astronomy, geography, and geology. |
| cosmology | The general science of the universe. |
| cosmopolitan | Common to all the world. |
| cosmopolitanism | A cosmopolitan character. |
| cosmos | The world or universe considered as a system, perfect in order and arrangement. |
| counter-claim | A cross-demand alleged by a defendant in his favor against the plaintiff. |
| counteract | To act in opposition to. |
| counterbalance | To oppose with an equal force. |
| countercharge | To accuse in return. |
| counterfeit | Made to resemble something else. |
| counterpart | Something taken with another for the completion of either. |
| countervail | To offset. |