The origin of the word goes long before it's use in the US for cannabis. 420 is common term in Indian subcontinent used for someone who is a thief/trickster/clever in mischievous way. The word originates by Penal Code of 1860 instituted by the colonial government of British India. Section 420 covers offences relating to cheating and dishonestly.

I am pretty sure someone from Indian subcontinent (pakistan, india, bangladesh), probably students, tricked some American pot smokers into using the word for themselves back in 1960s or 1970s. What else could explain that weird coincidence? In that sense they were "420" (mischievous trickster) who tricked people into using a (bad) Indian slang for themselves
Look, lets tell American pot smokers in our school that they should call themselves "420". (laughs Hehehee )
by Zuchi October 30, 2014
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a time to go smoke or the day everybody goes to smoke pot,or is also the day hitler was born
yo were gonna smoke on hitlers birthday its 420
by S.E. 24 January 19, 2009
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a word used to express the time or date in which you will meet up and smoke a whole fucking shitload of marijuana with all of your friends.
Also a holiday held on April 20 where everyone in the worlds celebrates the fact that they are raging potheads.
Hey Waylon, Happy 420....see you at 420 to smoke that dizzank.
by Trent April 20, 2004
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April 20th, 1889: Adolf Hitler is born. Yep, 420 is Hitler's birthday. Look it up. Bet you stoners didn't know that, huh?
"I think I'm gonna go celebrate 420."
"Fascist!"
by Sgtstumpy April 20, 2009
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1. April 20th.

2. National pot smoking day (April 20th).

3. A 2 person racing sailboat made by Vanguard and used in the olympics.
1. It's 420

2. it's 420 do you know where your weed is?

3. "lets go 420ing" "do u have the weed?" "no, lets go sailing!"
by iz March 28, 2005
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People on gaming platforms who think it's cool to put 420 in their name. It also applies to anyone with weed related names.
"Look at that guy right there! His name is sUpAkUsH420. I'm pretty sure he thinks he's cool because he smokes weed."
by A straight edge November 16, 2009
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(1) The ACTUAL country code for phone numbers assigned to the Czech Republic.
(2) A currently unused area code in the North American Numbering Plan which should totally be assigned to Denver, Colorado in place of 303 or Ann Arbor, Michigan in place of 734.
(3) A major pot-smoking holiday
(4) The actual page count of the novel "Nobody's Property" whose main character consumes medical marijuana to treat mental disorders.
Mary: What's the country code for Prague?
Jane: Well, it's in the Czech Republic, so 420...
Mary: No way!
Jane: Really. I shit you not!
by DaisukeDoki October 18, 2017
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