On the definition of cannabinoids: botanical? chemical? pharmacological?

Cannabinoids (or presumed synonyms such as cannabinols or cannabis-like agents) have been variously defined in botanical, chemical, or pharmacological terms, with unfortunate consequences. Botanical definitions include inactive substances such as cannabigerol, as well as alkaloids and other secondary constituents of Cannabis sativa, but exclude synthetics such as levonantradol and nabilone. Chemical definitions include inactive close analogs of THC but exclude a growing number of substances structurally remote from THC that share its actions. Pharmacological definitions have depended on relatively nonspecific or vague behavioral endpoints. However, animal testing methodology has recently been developed that can identify and quantify agents that share THC's unique subjective effects. To avoid preexisting ambiquity in the word cannabinoids, the term cannabimimetics has been coined to include all such agents, regardless of origin or structure. Such a classification emphasizes research toward improved biological selectivity and therapeutic advance. While no totally noncannabimimetic agents with potent analgesic effects have yet been identified among derivatives of THC, selectivity has been uncovered for levonantradol, HHC (racemic-9-nor, 9-beta-OH-hexahydrocannabinol) and several structurally related compounds.