Source : Webster's Revised Unabridged Dictionary (1913)

Etiological \E`ti*o*log"ic*al\, a.
   Pertaining to, or inquiring into, causes; [ae]tiological.

Source : WordNet®

etiological
     adj 1: of or relating to the philosophical study of etiology [syn:
            {etiologic}, {aetiological}, {aetiologic}]
     2: relating to the etiology of a disease; "etiological agent"
        [syn: {etiologic}, {aetiological}, {aetiologic}]