I've been wondering for some time: why defraud? Why don't we simply fraud people?
Whatever the reason, we've certainly been defrauding people for a long time. The word comes from the Anglo-French defrauder, from the Latin defraudare, from dē- plus fraus, which means fraud.
That dē- means away, or out of, in Latin, and there are many English words when a de- at the beginning of a word still means more or less the same thing - words like defrost, defrock, dehydrate - but then there are many more words where the de- at the beginning of a word means something rather different. De- in the words decompose and delegitimise means to reverse; and then there are instances where de- can make a word more intense, as in the word devote; or there's the word detest, where the de- turns the rest of the word into something horrible.
The word defraud, which started me thinking about this, is one of the making-it-more-intense ones.
I still can't honestly say I understand exactly why we don't fraud people. But I shall happily devote myself to them, all the same.