A research compound is a chemically defined substance — often, in this catalog, a peptide — supplied so that its properties, mechanisms, or effects can be studied under controlled laboratory conditions. “Research Use Only” is the label attached to a compound supplied for exactly that purpose and no other: not for human consumption, not for veterinary use, and not for diagnostic or therapeutic use.
What separates a research compound sold this way from an approved medicine is regulatory status and intended use, not necessarily the molecule itself — the same or a related molecule can exist in both worlds, as is the case for more than one compound in this catalog. See each compound’s hub article for what its own regulatory status actually is.