| cosmopolitan | Familiar with and at ease in many different countries and cultures | |
| corroborate | To confirm or support something with additional evidence; to make more certain | |
| cordial | Warm and friendly | |
| copious | Abundant in supply or quantity | |
| conundrum | A confusing and difficult problem or question | |
| contumacious | Stubbornly or willfully disobedient to authority | |
| consternation | Feelings of anxiety or dismay, typically at something unexpected | |
| conspicuous | Standing out so as to be clearly visible | |
| conscientious | Wishing to do one's work or duty well and thoroughly | |
| connoisseur | An expert judge in matters of taste | |