or 4/20 or 4:20

[ fawr-twen-tee, fohr‐ ]
/ ˈfɔrˈtwɛn ti, ˈfoʊr‐ /

noun Slang

marijuana: Are you carrying any 420 on you?
marijuana drug use: Police presence at the concert discouraged 420.The guys at the party were all 420-friendly.
the twentieth day of the fourth month, or the time 4:20, when referenced as a day or time for cannabis consumption or the celebration of marijuana culture: The head shop has a big pipe sale every year on 420.

Origin of 420

First recorded in 1970–75; a code word derived from the meeting time of a particular group of marijuana smokers in 1971, later popularized by fans of the band the Grateful Dead
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019