From Latin *pensare* ("to weigh, to consider"), a frequentative form of *pendere* ("to weigh"). The metaphor of "weighing" ideas in one's mind evolved into the general sense of thinking. The same Latin root gives English *pensive* and *ponderous*.

French speakers use *penser* in a slightly more deliberate, reflective way than English "think" in casual speech — for quick gut reactions, *trouver* ("Je le trouve bizarre" — I find it weird) is often preferred over *penser*. Also watch out: *penser à* means "to think about/of someone or something" (Je pense à toi — I'm thinking of you), while *penser de* means "to have an opinion about" (Qu'est-ce que tu penses de ce film? — What do you think of this film?). Mixing up *à* and *de* here is one of the most common learner errors.