/ˈkrɛdɪbəl/
[adjective] Able to be trusted or believed; seeming true or realistic enough that people are willing to accept it.
Every time you trust a stranger's story, you are using a word built on the same ancient root as 'creed' and even 'credit card'.
The story of 'credible' begins in ancient Rome, with the Latin verb 'credere', meaning 'to believe, to trust, or to entrust something to someone.' This verb was itself inherited from a much older Proto-Indo-European root, '*kred-dʰeh₁-', which combined the ideas of 'heart' and 'to place' — so at its very deepest origin, to believe in something meant literally to place your heart in it. That image of wholehearted trust is quietly embedded in every modern use of the word.
From 'credere', Latin formed the adjective 'credibilis', meaning 'worthy of belief' or 'that which can be believed.' The suffix '-ibilis' worked much like the English '-able', turning a verb into an adjective that described a quality or possibility. 'Credibilis' passed into Late Latin and then into Old French as 'crédible', and it was through this French channel that the word arrived in English during the late 14th century, at a time when English was absorbing enormous quantities of French and Latin vocabulary following the Norman Conquest.
When 'credible' first appeared in English writing, it carried a relatively simple meaning: something that could be believed without great difficulty. Over the following centuries, the word broadened slightly in tone, picking up connotations not just of logical believability but of trustworthiness and reliability — qualities that belong to a person or source, not just to a statement. By the 16th and 17th centuries, writers were regularly using it to describe witnesses, testimony, and accounts that deserved public confidence.
What makes 'credible' particularly interesting is the extraordinarily large family of English words it belongs to. All of them trace back to that same Latin 'credere'. Latin 'credere' → Old French 'creance' → English 'credence' (the trust you give to something). Latin 'credere' → Latin 'creditum' (a loan, something entrusted) → Italian 'credito' → English 'credit'. Latin 'credere' → Latin 'credo' (I believe) → English 'creed'. Latin 'credere' → Latin 'credulus' (too willing to believe) → English 'credulous'. Every one of these words carries that ancient idea of placing trust somewhere.
The word also has an interesting shadow: its near-opposite, 'incredible', arrived in English around the same time and has had a far more dramatic career. While 'credible' remained a relatively sober, factual word used in law, journalism, and public affairs, 'incredible' gradually drifted from meaning 'impossible to believe' toward a general expression of amazement — 'that was incredible!' — a journey that shows how positive words often stay literal while negative words drift into emotion. Today, 'credible' still does its quiet, serious work in politics, science, and the courtroom, carrying its ancient cargo of trust wherever it goes.