(CNN)Former CIA Director John Brennan tweeted Friday that President Donald Trump's administration is a failing "kakistocracy," causing a dramatic increase in online look-ups of the rarely used word.
Former CIA director: Trump presidency is a 'kakistocracy'
"Your kakistocracy is collapsing after its lamentable journey," Brennan tweeted. "As the greatest Nation history has known, we have the opportunity to emerge from this nightmare stronger & more committed to ensuring a better life for all Americans, including those you have so tragically deceived."
Shortly after his tweet, Merriam-Webster wrote that the word, pronounced "kak-uh-STAH-kruh-see," means "government by the worst people."
According to the dictionary company, look-ups for the word increased by 13,700% on Friday.
Brennan's tweet was in response to attacks Trump made on former FBI Director James Comey. In two Friday morning tweets, Trump called Comey, whose new book discusses his tense relationship with the President and the Russia probe, a "proven LEAKER & LIAR."
"He leaked CLASSIFIED information, for which he should be prosecuted. He lied to Congress under OATH," Trump tweeted. "He is a weak and ... untruthful slime ball who was, as time has proven, a terrible Director of the FBI."
Last month, Brennan suggested that the President may be afraid of Russian President Vladimir Putin because the Russians might have compromising information on Trump.
"I think he is afraid of the President of Russia," Brennan said of Trump in an interview on MSNBC's "Morning Joe."
Asked why, Brennan said, "The Russians could have something on him personally that they could always roll out and make his life more difficult."
On Thursday, CNN obtained a copy of Comey's upcoming book, a scathing tell-all that provides a striking glimpse into Trump's presidency.
"What is happening now is not normal, ..." Comey writes. "It is not fake news. It is not okay."