Today's Latin word is CREDO. If you look at the parts of this verb - credo (credere), credidi, creditum - you get a very good clue about the Latin etymology of the word. Does that reduplicated -didi in the perfect from seem familiar? It should remind you of the Latin verb "to give," do (dare), dedi, deditum. The word credo is actually a compound of Latin cor ("heart, mind") and dare, meaning to "give heart" to something - in other words, "to trust" or "to believe."
We even use the first-person form of the verb "credo," as an English word. There are also many English words that are derived from this Latin stem, such as "credit," "creed," "credible," "incredible," and so on. Less easy to recognize is the word "miscreant," which comes via the Old French mescreant, meaning to "badly believe," in the sense of being a heretic or an infidel. Later, the meaning came to refer to any kind of scoundrel or villain, not necessarily in a religious context.
As you would expect in a word that is a compound of dare, the verb credere takes a dative complement: verbis tuis credo, "I believe my words" or "I put my trust in your words." The verb can also introduce indirect speech with the accusative and infinitive: Credo Deum esse.
Here are some examples of today's word in Latin sayings and proverbs; for more information, see the page at the Scala Sapientiae, which contains notes on some of the proverbs cited below, as well as additional proverbs:
Quod video, id credo mihi.
Quod non legitur, non creditur.
Vide et crede.
Ne omnibus credas.
Non omni verbo credas.
Non omnibus crede.
Id quod volunt, credunt quoque.
Non opus est verbis; credite rebus.
Non est credendum omni verbo.
Tibi ut vincas est credendum.
Male creditis hosti.
Agere sequitur credere.
Ne aliis de se quisquam plus quam sibi credat.
Virtuti melius quam fortunae creditur.
Ore lego, corde credo.
Beati qui non viderunt, et crediderunt.
Contra spem in spem credidit.
Quod volumus, facile credimus.
Omnia quae dicunt homines tu credere noli.
Plus aliis de te, quam tu tibi, credere noli.