Source:http://linkedlifedata.com/resource/umls/id/C1444748
NCI: Something that sets into motion some course of events; a device that activates or releases or causes something to happen.,NCI: In medicine, a specific event that starts a process or that causes a particular outcome. For example, chemotherapy, painful treatments, or the smells, sounds, and sights that go with them may trigger anxiety and fear in a patient who has cancer. In allergies, exposure to mold, pollen or dust may trigger sneezing, watery eyes, and coughing.