Etiology (; alternatively spelled aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek word αἰτιολογία (aitiología), meaning "giving a reason for" (from αἰτία (aitía) 'cause' and -λογία (-logía) 'study of'). More completely, etiology is the study of the causes, origins, or reasons behind the way...