A harangue is more than a speech, louder than a discussion, and nastier than a lecture. It is a verbal attack that doesn't let up, delivered as a verb or received as a noun. Either way, it's pretty unpleasant.
The word harangue developed its modern spelling around 1530, when the word was recorded as harangue in French. The word, meaning a strong, nasty rant, appears to have evolved from the Old Italian word aringa, probably from the word for a public square or place for public speaking. This in turn appears to have evolved from a Germanic word related to ring, as in "circular gathering," which is clearly similar to the Italian meaning.