epiphenomenonnoun [ C ]
uk/ˌep.ɪfəˈnɒm.ɪ.nən//ˌep.ɪfəˈnɑː.mə.nɑːn/plural epiphenomena /-ə/formala phenomenon (= something that exists and can be seen, felt, etc.) that exists at the same time as another one but is not related to it:
Are the observations clues to the cause of the condition or merely epiphenomena?