The Collaborative International Dictionary of English v.0.48:

oecology \oe*col"o*gy\ ([-e]*k[o^]l"[-o]*j[y^]), n. [Gr. o'i^kos
   house + -logy.] (Biol.)
   The various relations of animals and plants to one another
   and to the outer world; -- now more commonly spelled
   ecology. [Also spelled ecology.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

ecology \ecology\ ([-e]*k[o^]l"[-o]*j[y^]), n. [Gr. o'i^kos
   house + -logy.] (Biol.)
   the branch of biology concerned with the various relations of
   animals and plants to one another and to their surrounding
   environment.
   [PJC]

WordNet (r) 3.0 (2006):

ecology
    n 1: the environment as it relates to living organisms; "it
         changed the ecology of the island"
    2: the branch of biology concerned with the relations between
       organisms and their environment [syn: ecology, bionomics,
       environmental science]

Moby Thesaurus II by Grady Ward, 1.0:

70 Moby Thesaurus words for "ecology":
   aerobiology, agrobiology, anatomy, animal physiology, anthropology,
   astrobiology, autecology, bacteriology, biochemics, biochemistry,
   biochemy, bioecology, biological science, biology, biometrics,
   biometry, bionics, bionomics, biophysics, botany, cell physiology,
   commensality, comparative anatomy, conchology, cryobiology,
   cybernetics, cytology, ecoclimate, ecodeme, ecosystem,
   electrobiology, element, embryology, entomology, enzymology,
   ethnobiology, ethology, exobiology, genetics, gnotobiotics,
   helminthology, herpetology, ichthyology, life science, malacology,
   mammalogy, medium, microbiology, molecular biology, ornithology,
   parasitism, pharmacology, physiology, protozoology, radiobiology,
   symbiosis, symbiotics, synecology, taxidermy, taxonomy, virology,
   xenobiology, zoogeography, zoography, zoology, zoonomy,
   zoopathology, zoophysics, zootaxy, zootomy