The Collaborative International Dictionary of English v.0.48:

Phenology \Phe*nol"o*gy\, n. [Contracted from Phenomenology.]
   (Biol.)
   The science of the relations between climate and periodic
   biological phenomena, as the migrations and breeding of
   birds, the flowering and fruiting of plants, etc. --
   Phe`no*log"ic*al, a. -- Phe`no*log"ic*al*ly, adv. --
   Phe*nol"o*gist, n.
   [Webster 1913 Suppl.] Phenolphthalein