- contraband: anything that is against the law to buy or sell
- contradict: to express the opposite
- contrarian: a person who thinks differently from other people; a person who does the opposite of what is expected
- contrary: – completely different; opposite in nature, opinion, or action
- contrast: to look at different things to see how they are opposites or not related
- counterbalance: a weight used to balance an opposite weight
- counterclockwise: in the direction that is opposite in movement of the directions on the hands on a clock
- counterexample: an example used to support a claim or statement that is the opposite of another claim or statement
- counterfeit: being the opposite of real; fake or artificial
- counterintuitive: goes against your gut feeling or common sense