Source : Webster's Revised Unabridged Dictionary (1913)

Biology \Bi*ol"o*gy\, n. [Gr. ? life + -logy: cf. F. biologie.]
   The science of life; that branch of knowledge which treats of
   living matter as distinct from matter which is not living;
   the study of living tissue. It has to do with the origin,
   structure, development, function, and distribution of animals
   and plants.

Source : WordNet®

biology
     n 1: the science that studies living organisms [syn: {biological
          science}]
     2: characteristic life processes and phenomena of living
        organisms; "the biology of viruses"
     3: all the plant and animal life of a particular region [syn: {biota}]