General Categories:
* Study of:
* Biology (study of life)
* Geology (study of the Earth)
* Psychology (study of the mind)
* Sociology (study of society)
* Anthropology (study of humans)
* Meteorology (study of weather)
* Criminology (study of crime)
* Etymology (study of word origins)
* Theology (study of religion)
* Ecology (study of the environment)
* Neurology (study of the nervous system)
* Immunology (study of the immune system)
* Paleontology (study of fossils)
* Cardiology (study of the heart)
* Oncology (study of cancer)
* Morphology (study of form)
* Taxonomy (study of classification)
* Cosmology (study of the universe)
* Astrobiology (study of life in the universe)
* Archeology (study of past cultures)
* Epistemology (study of knowledge)
* Philology (study of languages)
* Phrenology (study of the skull)
More Specific:
* Medical:
* Gastroenterology (study of the digestive system)
* Ophthalmology (study of the eyes)
* Dermatology (study of the skin)
* Endocrinology (study of hormones)
* Gerontology (study of aging)
* Other:
* Petrology (study of rocks)
* Volcanology (study of volcanoes)
* Seismology (study of earthquakes)
* Dendrochronology (study of tree rings)
* Mycology (study of fungi)
* Ornithology (study of birds)
* Ichthyology (study of fish)
* Entomology (study of insects)
* Herpetology (study of reptiles and amphibians)
* Mammalogy (study of mammals)
This is just a small sample of the many words that end in "-ology". If you're looking for a specific word, it's helpful to think about the subject matter and then combine it with "-ology."