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-logy

Also ‑ology.

A subject of study or interest; speech or language.

French ‑logie or medieval Latin ‑logia, from Greek logos, word or speech.

Many examples relating to a field of study exist, of which a selection is given in the list below. Almost all precede the ending with ‑o‑; two common exceptions are genealogy and mineralogy, but under the influence of the majority these are also often seen spelled with o.

The ending is active in forming new words. It is often used to create temporary or humorous forms, as with gizmology, the subject of gizmos or gadgets; sleazology, the investigation or study of sordid and corrupt behaviour; mindology, a facetious alternative to psychology. Ology has existed since the early nineteenth century as an informal term for any subject of study or branch of knowledge.

A second, less common, sense is related to that of ‑logue, indicating some characteristic of speech or language, or a type of discourse. Examples include terminology (medieval Latin terminus, a term); tautology (Greek tauto‑, same), the saying of the same thing twice over in different words; symbology, the study or use of symbols; and apology (Greek apologia, a speech in one's own defence, from apo, away). Anthology comes from the related Greek suffix ‑logia, a collection, plus anthos, flower, because it originally meant a collection of flowers of verse, choice epigrams and the like. See also ‑logist and ‑logical.

Examples of words in -logy
Origins are from Greek unless otherwise stated.

anthropology

the study of humankind

anthrōpos, human being

archaeology and US also archeology

the study of human history and prehistory through the excavation of sites and the analysis of physical remains

arkhaios, ancient

astrology

the study of the movements and relative positions of celestial bodies interpreted as having an influence on human affairs and the natural world

astron, star

biology

the study of living organisms

bios, life

biotechnology

the exploitation of biological processes for industrial and other purposes

bios, life, plus technē, art, craft

chronology

the study of historical records to establish the dates of past events

khronos, time

ecology

the branch of biology that deals with the relations of organisms to one another and to their physical surroundings

oikos, house

geology

the science which deals with the physical structure and substance of the earth, their history, and the processes which act on them

, earth

gynaecology and US gynecology

the branch of physiology and medicine which deals with the functions and diseases specific to women and girls, especially those affecting the reproductive system

gunē, gunaik‑, woman, female

meteorology

the branch of science concerned with the processes and phenomena of the atmosphere, especially as a means of forecasting the weather

meteōron, of the atmosphere

microbiology

the branch of science that deals with micro-organisms

mikros, small, plus bios, life

neurology

the branch of medicine or biology that deals with the anatomy, functions, and organic disorders of nerves and the nervous system

neuron, nerve, sinew, tendon

pathology

the science of the causes and effects of diseases

pathos, suffering, disease

pharmacology

the branch of medicine concerned with the uses, effects, and modes of action of drugs

pharmakon, drug

physiology

the branch of biology that deals with the normal functions of living organisms and their parts

phusis, nature

psychology

the scientific study of the human mind and its functions, especially those affecting behaviour in a given context

psukhē, breath, soul, mind

sociology

the study of the development, structure, and functioning of human society

Latin socius, companion

technology

the application of scientific knowledge for practical purposes, especially in industry

technē, art, craft

theology

the study of the nature of God and religious belief

theos, god

topology

the study of geometrical properties and spatial relations unaffected by the continuous change of shape or size of figures

topos, place

zoology

the scientific study of the behaviour, structure, physiology, classification, and distribution of animals

zōion, animal

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