In the three weeks since the House of Representatives opened its formal impeachment inquiry into President Donald Trump, the battle of words has been unrelenting. Politicians have supplied a steady stream of sound bites. Pundits have logged hours on TV news shows. Op-Ed writers in newspapers large and small have laid out their cases.

So which, if any, of these words are resonating with the public? One way to get a sense of that is to examine the words that are driving people to online dictionaries. And by that measure, the word at the center of it all — impeach — has definitely caught people's attention.

"We saw a 3,600 percent increase in the lookups for that word, impeach [on September 24]," said Peter Sokolowski, editor-at-large for Springfield-based Merriam-Webster. "And it was already trending fairly high."

The word impeach has been used in the same legal sense since the 1500s, back in England — the country from which America's founding fathers drew so much inspiration for our own system of government. Much of the language of that English system was introduced by the French following the Norman invasion in 1066, which is why French words are so common in our legal system.

"The word [impeach] is a pretty transparently French word," said Sokolowski. "And if you know modern French there’s the verb empêché, which means to impede or to stop or to halt."

Sokolowski points out that while we often associate impeachment with the actual removal of an official from office, it’s important to remember that that’s not what it means.

"What it means is to charge a public official — before a competent tribunal — with misconduct in office," he explained. "It’s really just to bring charges. It’s really more like an indictment."

And "impeach" is not the only word that has caught the attention of the public as this story has unfolded. The term "quid pro quo" has been looked up more than 99 percent of all other words and terms in the dictionary over the past few weeks.

"In Latin it basically just means this for that, or something for something else — an exchange," said Sokolowski. "That word also spiked because it’s a big part of the story."

Words that have been embraced by President Trump in recent weeks have also been driving searches. Coup – another French word – saw a 3,200 percent increase on Oct. 2, when the president described the impeachment inquiry as such in a tweet.

And just last week, President Trump defended his decision not to allow state department officials to testify, calling the proceedings in the House a "kangaroo court." Lookups for that term spiked 11,000 percent. Merriam-Webster defines kangaroo court as “a mock court in which the principles of law and justice are disregarded or perverted.” And while it sounds like something that may have arisen in Australia during its years as an English penal colony, it’s actually a fairly modern term coined right here in the U.S.

"It basically started in the 1840s and 1850s around the time of the California gold rush," said Sokolowski.

Sokolowski said its not clear why the term kangaroo was embraced. But in wild and woolly, fast-growing mining towns in Western territories outside of any clear jurisdiction, ad hoc justice systems earned the nickname.

"In unincorporated districts where there weren't official lawmen, some kind of law and order had to be established," said Sokolowski. "And kangaroo court was the way that courts of law were referred to in those pre-state territories."

Sokolowski said there are a few other words the folks at Merriam-Webster are watching closely — including "treason," "bribery," and the term "high crimes and misdemeanors." These are all specifically laid out in the Constitution as reasons for an impeachment. Sokolowski said that the term "high crimes and misdemeanors" is the least specifically defined of the bunch. The two are essentially synonyms, he added, noting a detail worth remembering about that modifier, “high.”

"Really it doesn’t mean great crime or big crime. It means a crime made in high office," he said. "So it has to do with the nature of the person committing the crime not the nature of the crime itself."

And while we don’t know how this will all play out in the coming weeks and months, one thing seems clear. People are paying attention — and whatever happens they’ll be turning to the dictionary to help them understand.