What Does "420" Mean, and Why?

Hint: There aren't 420 chemical compounds in cannabis

4/20 celebration
Justin Sullivan / Getty Images News / Getty Images

First, let's talk about what "420" doesn't mean.

4/20 isn't the date Bob Marley died — he actually succumbed to cancer on 5/11/81 — no matter what you may have heard or read to the contrary. It's not his birthday, either.

420 isn't the number of a bill in U.S. Congress aiming to legalize weed, despite many people believing it is.

420 isn't the police or penal code for marijuana possession in California (or any other state), though many people are convinced of that, as well.

Nor is it is the number of chemical compounds in cannabis, the pot plant, though lots of folks are fond of stating so.

"420" and Weed

What 420 is — whether expressed in the form 4:20 (as a time of day), 4/20 (as a calendar date) or just the unadorned numeral 420 (pronounced "four-twenty") — is a universal, unofficial symbol for the use and enjoyment of marijuana. As a matter of fact, 4/20 (April 20) has come to be known in certain circles as "Marijuana Appreciation Day," or, simply, "Weed Day."

Notwithstanding the many and various urban legends that have grown up around the meaning of "420" and its connection with marijuana, the true story behind it is surprisingly prosaic.

In the early 1970s a small group of hippie stoners at San Rafael High School in northern California used to meet at a designated location every day at 4:20 p.m. to smoke weed. They did this so regularly that among members of the group — who called themselves "the Waldos" — the expression "420" became a euphemism for "time to light up."

The catchphrase spread beyond their immediate circle, beyond the high school they attended and ultimately beyond California, so that within a decade or two pot smokers were using it across the country, and indeed the world over.

How popular is the expression today? A Google search on the paired terms "420" and "marijuana" brings up roughly 20 million results, including a link to the website of 420 Magazine, a publication wholly dedicated to what its publishers refer to as "cannabis awareness."

Happy 4/20. The date has arrived!

Update #1: We now have a new, revised account of the origin of "420" from — where else? — 420 Magazine editor Rob Griffin. Griffin says the Waldos version isn't entirely accurate.

Update #2: Naturally, the accuracy of Rob Griffin's historical revisionism is being challenged by members of the original Waldos.

More wacky etymology:
Does "Dork" Really Mean What They Say It Does?
The Origin of the F-Word
The Origin of the S-Word
The Origin of "The Finger"