Impeach spiked on April 17th and 18th, following news reports of the impeachment of Dilma Rousseff, the president of Brazil, by that country’s Chamber of Deputies. In Brazil, as in the United States, the lower house of Congress votes on impeachment, and the matter is then passed to the Senate.
Although impeach has been used in the English language since the 14th century, it has not always been restricted to the commonly used modern sense of "to charge (a public official) with a crime done while in office"; other meanings over the years have included the bringing of a more generalized accusation, the act of hindering or impeding someone, and the act of challenging or disparaging someone ("he has impeached my honor").
The word came to Middle English from the Middle French empecher, which was itself descended from the Late Latin word impedicare ("to entangle, fetter"). Impedicare contains the root ped- (meaning "foot") and so impeach shares an etymological connection with many other English words, such as breviped ("having short legs") and expedite ("to remove the difficulties from").
Two United States presidents have been impeached: Andrew Johnson, in 1868, and Bill Clinton, in 1998. Both were acquitted. A third president, Richard Nixon, came close in 1974, as articles for impeachment were drawn up by the House, but he resigned before the matter was put to a vote.