research (n) - diligent and systematic inquiry or investigation into a subject in order to discover or revise facts, theories, applications, etc.
trial (n) - the act of trying, testing, or putting to the proof. The words "trial" and "study" are interchangeable regarding clinical research.
Clinical Research is a diligent, systematic investigation in which people, or data or samples provided by people, are studied to understand health and diseases. Clinical trials test new treatments (medicinal or devices) for diseases or chronic conditions such as migraines.