The definition of insanity is to do the same thing over and over and expect different results, right? Wrong. Though that quote was made popular by a variety of movies, TV, and video games, even some of history’s greatest minds like Albert Einstein and Mark Twain, it's not quite right.

The Oxford English Dictionary defines insanity as "the state of being seriously mentally ill; madness, lunacy.” Yet insanity isn’t a medical term — it's a legal one, according to the hosts of scientific YouTube channels ASAP Science and BrainCraft. Apparently, in the U.S., a defendant can plead insanity if, at the time of a crime, the defendant can prove experiencing a severe mental disease or defect. This would mean the defendant was unable to appreciate the nature and quality or the wrongness of his acts.

In most cases, the hosts explain, we use the word insane to describe what's not considered normal, like a basketball player’s vertical leap, a horse's speed, or a video game's clean, quality graphics. However, insanity is meant to describe LeBron James' dunk, but rather it's meant to describe mental illness.

According to the National Institute of Mental Health, four percent of the population suffers from a severe mental disorder, which can interfere with their daily life. Additionally, twenty percent of adults in the country will suffer from a mental illness at some point in time during any year, and half of the population will need some type of treatment.

While mental illness is still stigmatized (just look at California), we are getting better at recognizing when someone is suffering from a mental illness. So, although you might think that something is insane, grab a thesaurus and find a different word that will better describe the backflipping, blow-torch juggling, three-legged hippo you just saw ramp across the Grand Canyon on a suped-up Segway.

Watch the video above for more on insanity, and it's prescribed meanings.