“Synthetic marijuana” is a common, but misleading, term that refers to a class of substances more accurately called cannabinoid receptor agonists or synthetic cannabinoids. Whereas marijuana usually refers to the dried flowered buds of the actual plant, which derives its main psychoactive effect through THC, synthetic cannabinoids get their name from their action on various cannabinoid receptors in the brain.
People in public office, the media, and law enforcement often sacrifice accuracy for simplicity and use the term “synthetic marijuana” or the brand names of products sold, such as “Spice” or “K2,” that are known to contain various synthetic cannabinoids.