It’s a Mexican slang word mustered up by Wm. R. Hearst the San Francisco paper magnet and the DuPont chemical family of the early 30′s who coined the word to prevent competition from the 50,000 products that can be derived from Hemp/Cannabis (Sativa/Indicia strains).
DuPont found out the family could produce many synthetics from petroleum that Hemp already provided.
Hearst wanted to protect his paper empire – not only news paper supplies, but his timber holdings under Kimberly Clarke. Their concern was to cut the competition off at the knees!
With Hearst he spread the evils of this new weed in his news papers (and other derogatory slang terms) called Marihuana, a word no one had heard before. He gave lots of space in his papers to rile the people about what he called this evil drug.
"Freedomless, Will work for Liberty"