Cannabinoid is a generic term for: 1. * Phytocannabinoids, compounds found in the Cannabis plant that are structurally related to Tetrahydrocannabinol (THC). 2. * Endocannabinoids that are found in the nervous and immune systems of animals and that activate cannabinoid receptors. 3. * Synthetic cannabinoids, a structurally diverse class of mostly synthetic substances that bind to cannabinoid receptors.