CNN  — 

On this day in 1998, the world had to dig deep and ask itself, “What does the word ‘is’ mean?” Thank President Bill Clinton, who caused the linguistic existential crisis during his grand jury testimony regarding his affair with Monica Lewinsky.

The entire case was long, drawn-out and complicated, starting with the Whitewater investigation, winding into Paula Jones’ sexual harassment charges and ending with the revelation of Clinton’s affair with Lewinsky. If you want to dive down that rabbit hole, I suggest CNN’s timeline.

Here are the basics: Independent counsel Ken Starr had been looking into the Clintons for years, starting with their Whitewater real estate investments. The Paula Jones sexual harassment charges led to Starr uncovering the Lewinsky affair. Clinton denied having a sexual relationship with Lewinsky while he was under oath for a deposition for the Jones case. That played into the multiple charges of perjury and obstruction of justice that Starr levied against the President.

Clinton was called before a grand jury, becoming the first sitting president to appear before one regarding an inquiry focused on his behavior. That’s where one of the most infamous semantics quandaries in history went down. You can watch it in the Instagram video above.

The question: “Whether or not Mr. Bennett knew of your relationship with Ms. Lewinsky, the statement that there was ‘no sex of any kind in any manner, shape or form, with President Clinton,’ was an utterly false statement. Is that correct?”

“It depends on what the meaning of the word ‘is’ is,” Clinton responded.

The definition of the word “is,” according to Webster’s Dictionary, is: “present tense third-person singular of be.” Obviously.

Later that day, the President said of his testimony, “While my answers were legally accurate, I did not volunteer information.” He also came clean on his affair with Lewinsky.

Spoiler: Clinton was not removed from office. The House voted for impeachment. The Senate acquitted Clinton, although it was probably closer than Clinton might have hoped.