the cause or origin of something, esp a disease or abnormal condition
the study of all the causes of something, esp a disease
aetiologic /ˌeeti·əʹlojik/ adj
aetiological /-ʹlojikl/ adj
aetiologically /-ʹlojikli/ adv
[via medieval Latin from Greek aitiologia statement of causes, from aitia cause]