disabuse

We know the verb "abuse" as a word meaning "to misuse," "to mistreat," or "to revile." But when "disabuse" first appeared in the early 17th century, there was a sense of "abuse," now obsolete, that meant "to deceive." Sir Francis Bacon used that sense, for example, when he wrote in 1605, "You are much abused if you think your virtue can withstand the King's power." The prefix dis- has the sense of undoing the effect of a verb, so it's not surprising that disabuse means "to undeceive." English speakers didn't come up with the idea of joining "dis-" to "abuse" all on their own, however. It was the French who first appended their prefix "dés-" to their verb "abuser." English "disabuse" is modeled after French "désabuser."