| Term | Definition |
| CRED (CREDIT) | believe |
| Accredited | officially authorized or recognized; provided with credentials |
| Credence | belief as to the truth of something |
| Credentials | documents, letters, references, etc., that inspire belief or trust |
| Credible | believable |
| Credit | belief; faith; trust |
| Credulous | too ready to believe; easily deceived |
| Creed or Credo | summary of principles believed in or adhered to |
| Discredit | 1. cast doubt on; refuse to believe; 2. take trust or credit away from; disgrace |
| Incredulity | disbelief |
| FID | faith, trust |
| Affidavit | sworn written statement made before an authorized official |
| Bona | fide made or carried out in good faith; genuine |
| Confidant | one to whom secrets are entrusted |
| Confident | having faith in oneself; self-reliant; sure |
| Confidential | communicated in trust; secret; private |
| Diffident | lacking faith in oneself; timid; shy |
| Fidelity | 1. faithfulness to a trust or vow; 2. accuracy; faithfulness of sound reproduction |
| Infidel | one who does not accept a particular faith; unbeliever |
| Perfidious | false to a trust; faithless |
| Perfidy | violation of a trust; treachery; faithlessness; disloyalty |
| GRAT | pleasant, thank, favor |
| Gracious | pleasant; courteous; kindly |
| Grateful | feeling or expressing gratitude; thankful; obliged |
| Gratify | give or be a source of pleasure and satisfaction |
| Gratis | without charge or payment; free |
| Gratitude | thankfulness |
| Gratuitous | uncalled for; lacking good reason; unwarranted |
| Gratuity | present of money in return for a favor or service; tip |
| Ingrate | ungrateful ("not thankful") person |
| Ingratiate | establish (oneself) in the favor or good graces of another |