The suffix '-OLOGY' in BIOLOGY, GEOLOGY, and PSYCHOLOGY indicates:

The suffix -OLOGY means the study or science of a subject. BIOLOGY is the study of life (bio = life), GEOLOGY the study of the earth (geo = earth), and PSYCHOLOGY the study of the mind (psych = mind). When you see -OLOGY ending an unfamiliar word, you can infer it names a field of study. Combine that with the root to estimate the topic — for example, 'zoology' (zoo = animal) is the study of animals. Knowing common suffixes like -OLOGY (study of), -PHOBIA (fear of), and -ITIS (inflammation) helps decode technical vocabulary on the test.