* Credible: believable, trustworthy
* Credit: belief, trust, financial borrowing
* Credential: a document that provides evidence of a qualification
* Credence: belief, trust, acceptance as true
* Credulous: easily persuaded to believe something
* Creditor: a person or organization to whom money is owed
* Creditworthy: considered financially reliable
* Accreditation: official recognition of a qualification or institution
* Credo: a statement of belief or principles
* Incredible: unbelievable, amazing
* Discredit: to damage the reputation of someone or something
* Accredit: to officially recognize a qualification or institution
* Recredit: to give credit again
Let me know if you'd like more examples or a specific category of "cred-" words.