1. Capable of being believed; believable or plausible: a credible witness; a credible explanation. See Synonyms at plausible.
2. Considered capable of achieving a goal: The party must nominate a credible candidate for governor.
3. Being of sufficient military capability to deter an attack or carry out an operation successfully: credible military force.
[Middle English, from Latin crēdibilis, from crēdere, to believe; see kerd- in the Appendix of Indo-European roots.]
Usage Note: Credible is widely but incorrectly used where credulous would be appropriate. Credulous means "believing too readily" or "gullible," as in He was credulous (not credible) enough to believe the manufacturer's claims.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.