One word that is synonymous with "discover" and also starts with the letter "c" is "uncover."

To uncover something means to reveal or bring to light something that was previously hidden or unknown. For example, a detective might uncover a crucial piece of evidence that helps solve a crime, or a researcher might uncover new information that changes the way we understand a particular topic.

Here are a few examples of the word "uncover" used in context:

• "The archaeologists were thrilled to uncover a previously unknown tomb filled with ancient artifacts."
• "After years of research, scientists finally uncovered the genetic basis for a rare disease."
• "The investigation into the company's finances uncovered evidence of fraud and embezzlement."

Overall, "uncover" is a useful and versatile word that can be used in a variety of contexts to describe the process of revealing something that was previously hidden or unknown.