etiology (n.) Look up etiology at Dictionary.com
also aetiology, aitiology, "science of causes or causation," 1550s, from Late Latin aetiologia, from Greek aitiologia "statement of cause," from aitia "cause, responsibility" (from PIE *ai-t-ya-, from root *ai- (1) "to give, allot;" see diet (n.1)) + -logia "a speaking" (see -logy). Related: Etiologic; etiological.