Source : Webster's Revised Unabridged Dictionary (1913)

Physiology \Phys`i*ol"o*gy\, n.; pl. {Physiologies}. [L.
   physiologia, Gr. ?; fy`sis nature + ? discourse: cf. F.
   physiologie.]
   1. The science which treats of the phenomena of living
      organisms; the study of the processes incidental to, and
      characteristic of, life.

   Note: It is divided into animal and vegetable physiology,
         dealing with animal and vegetable life respectively.
         When applied especially to a study of the functions of
         the organs and tissues in man, it is called human
         physiology.

   2. A treatise on physiology.

   {Mental physiology}, the science of the functions and
      phenomena of the mind, as distinguished from a
      philosophical explanation of the same.

Source : WordNet®

physiology
     n 1: the branch of the biological sciences dealing with the
          functioning of organisms
     2: processes and functions of an organism