As a prefix:
* Contraband: The customs agents seized the contraband goods from the smugglers.
* Contradict: Her statement contradicted everything the witnesses had said.
* Contraceptive: Doctors recommend using contraceptives to prevent unwanted pregnancies.
* Contraindication: The patient's allergy was a contraindication for the prescribed medication.
As an independent word:
* Contra: While the company's proposal had some strong points, there were also some serious contra arguments. (This usage is more common in business or legal settings)
Important Note: "Contra" is most commonly used as a prefix. It's less common to see it used as an independent word, and even then it is usually used in specific contexts.