...(o)logy

Every word with two compounds, the second being -(o)logy, is Greek and means a study of a particular subject, something said, or a way of speaking . Some of them are:

Biology. From Ancient Greek βίος, bíos, bio-, life + -λογία, -logía, -logy, branch of study, to speak. The study of all life or living matter.

Geology. From Ancient Greek γῆ, gē, earth + -logia, -logy. The science that studies the structure of the earth (or other planets), together with its origin and development, especially by examination of its rocks.

Genealogy. From Ancient Greek γενεαλογία, genealogia, from γενεά, genea, generation, descent and -λογία, -logia, study of. The study of families and the tracing of their lineages and history.

Trilogy. From Ancient Greek τρεῖς, treis, three + λόγος, logos, story, account. A three-part series.

Apology. From Ancient Greek ἀπολογία, apologia, a speech in defense, from ἀπολογοῦμαι, apologoumai, I speak in one's defense, from ἀπό, apo, from, off + λόγος, logos, speech.

Anthropology. From Ancient Greek ἄνθρωπος, anthropos, man, mankind, human, humanity + -logy. The holistic scientific and social study of humanity.