The word root “cred” means “to believe.” Different prefixes and suffixes are added to this root to create words that have to do with believing.
incredible - (adjective) not able to be believed, hard to believe [in- = not and -ible = able]
I found Bob’s incredible story about the elephant and the bicycle unlikely, but then he showed me some pictures and I knew he wasn’t making it up.
credible - (adjective) reasonable enough to be believed [-ible = able]
Sam was a credible witness whom I had never known to lie.
credulous - (adjective) willing to believe, especially without proof; gullible [-ous = full of]
Many credulous young children believe their parents’ tales about the Tooth Fairy, but others know exactly who put the money under their pillows.
incredulous - (adjective) not willing to believe; skeptical [in- = not; -ous = full of]
While some are certain that aliens live alongside people on Earth, most remain incredulous and believe evidence in support of these claims is purely fabricated.
credibility - (noun) the power to be believed; the ability to believe [-ility = ability]
Bob’s story that the dog ate all the cookies had no credibility because he had crumbs on his shirt. His tale tested my credibility and now I do not know if I can trust him anymore.
creed - (noun) a set of beliefs
The government prohibits discrimination based on sex, race, creed, or disability.
- Do not confuse “credible” with “credulous” or “incredible” with “incredulous.” Questions involving this distinction are common on standardized tests.
Read Vocabulary Examples of the use of incredulous and credible.
