By that standard pretty much everything is “partially” natural. You’re almost always going to have at least one starting material that was derived from a plant or other natural product.
Lysergic acid diethylamide, commonly known as LSD (from German Lysergsäurediethylamid) and by the nicknames acid and Lucy, is a semisynthetic psychedelic drug derived from ergot, known for its potent psychological effects.
By that standard pretty much everything is “partially” natural. You’re almost always going to have at least one starting material that was derived from a plant or other natural product.
Bring that up with chemistry, it’s their term.
https://en.wikipedia.org/wiki/Semisynthesis