“Words we think of today as leftovers from the 1960s are really leftover from the 1930s,” he said. But it is important to look even further back, he added. Terms like cannabis and ganja go back centuries, and have long been used to describe the plant and its medicinal properties.

Indeed, the word “marijuana” was introduced to the English language as recently as 1874 and was derived from Spanish, Mr. Sokolowski said. And it was the Spaniards who brought cannabis to Mexico’s land, which they hoped to cultivate for industrial-use hemp. They had a number of spellings for the word, including “mariguana” and “marihuana.” But unlike the word “cannabis,” it picked up a negative meaning.

In 2013, NPR wrote a thorough explanation of the word in which people said it had racist and anti-immigrant implications. In the piece, NPR cited news articles from the early 20th century suggesting that marijuana — or marihuana — was responsible for inciting violence among Mexicans who smoked it. It was sometimes called “loco weed.” (Loco means “crazy” in Spanish.)

That imagery was part of an anti-cannabis movement and helped to prompt a crackdown on illegal cannabis use, which culminated in the Marihuana Tax Act of 1937. “Suddenly the drug has a whole new identity,” NPR wrote.

Mr. Chong, who has argued in favor of legal cannabis, agreed. “It became evil,” he said.

Long before Snoop Dogg became a de facto ambassador for the cannabis industry, Mr. Chong, now 81, and his comedy partner, Cheech Marin, poked fun at stoner culture in their movies, playing affable smokers on the run from the police. “I was known as the pothead guy,” Mr. Chong said. In 1978’s “Up in Smoke,” they drive a van from Mexico to Los Angeles that is made of resin from cannabis plants. In 1981’s “Nice Dreams,” they sell marijuana out of an ice cream truck.