[ae]tiology

pathology \pa*thol"o*gy\ (-j[y^]), n.; pl. {pathologies}
   (-j[i^]z). [Gr. pa`qos a suffering, disease + -logy: cf. F.
   pathologie.]
   1. (Med.) The science which treats of diseases, their nature,
      causes, progress, symptoms, etc.
      [1913 Webster]

   Note: Pathology is general or special, according as it treats
         of disease or morbid processes in general, or of
         particular diseases; it is also subdivided into
         internal and external, or medical and surgical
         pathology. Its departments are {nosology},
         {[ae]tiology}, {morbid anatomy}, {symptomatology}, and
         {therapeutics}, which treat respectively of the
         classification, causation, organic changes, symptoms,
         and cure of diseases.
         [1913 Webster]

   2. (Med.) The condition of an organ, tissue, or fluid
      produced by disease.
      [Webster 1913 Suppl.]

   {Celluar pathology}, a theory that gives prominence to the
      vital action of cells in the healthy and diseased
      functions of the body. --Virchow.
      [1913 Webster]
    

aetiology \ae`ti*ol"o*gy\ ([=e]`t[i^]*[o^]l"[-o]*j[y^]), n. [L.
   aetologia, Gr. a'itiologi`a; a'iti`a cause + lo`gos
   description: cf. F. ['e]tiologie.]
   1. The science, doctrine, or demonstration of causes; esp.,
      the investigation of the causes of any disease; the
      science of the origin and development of things; etiology.
      AS
      [1913 Webster]

   2. The assignment of a cause.
      [1913 Webster]

   3. (Med.) The cause or origin of a disease. Now more commonly
      written {etiology}.
      [PJC + AS]