In English, you will find many words with the same suffix, or word ending. Three of the most common suffixes sound somewhat alike, and are often confused with each other. Here’s how to tell them apart, and some of the most common examples of each.

Ology

Ology is a real word, a noun taken from the common 5-letter suffix meaning a field or branch of study. It is the comprehensive, usually scientific, study of a particular subject, and there are many of them. The word is derived from the ancient Greek word logia, meaning the study of. In English, we use o as a connector to form compounds. More on that later. The plural of ology is ologies.

“He’s an expert in one of the ologies, I just can’t remember which one.”

You may be wondering about the common English word apology. Is it a science of something? It even has the same plural ending -ologies. However, apology has a very different origin. It is a compound from the Greek apo, meaning away from, and logos, meaning speech. Here, the o isn’t a connector, as it is a part of the word itself.

Here are some common ologies:

• Geology – The study of Earth, its structure and its development
• Biology – The study of living creatures
• Anthropology – The study of the development of humankind
• Criminology – The study of crime and its effects on society
• Meteorology – The study of weather and weather forecasting

Here are some of the more unusual, but real, ologies:

• Axiology – The study of human values and value judgements
• Eschatology – The study of finality, or the end of things
• Etymology – The study of the origin of words (I do this a lot in this blog)
• Phrenology – The study of the shape of a skull to determine someone’s character
• Scatology (This has two meanings, both real) –

1. The study of obscenity
2. The study of excrement

-Ography

Now that you’re all wondering why anyone would want to study some of those things, let’s consider the suffix -ography. Earlier I wrote that “In English, we use o as a connector to form compounds.” Graphy is the actual suffix, with o serving as the connector, and it comes from the French word graphie, meaning written form. Words with this suffix, then, are also fields of study but often done in writing or some form of artistic method. As with all things in the English language, this can be misleading, and there are exceptions. Here are some common -ographies:

• Biography – The study of a person’s life
• Photography – The art and practice of taking photographs
• Cartography – The study and art of the creation of maps
• Oceanography – The study of the Earth’s oceans
• Cinematography – The art and science of creating images for the cinema

Some -ographies are lists:

• Bibliography – The list of resources used by an author in researching a written work
• Filmography – A list of related films
• Discography – A list of related recordings

And some -ographies are just, well, odd:

• Steganography – The art and science of creating hidden images within images
• Cryptography – The art and science of writing and deciphering coded messages
• Tasseography – The art and science of reading tea leaves

-Onomy

If an ology is the study of a particular subject, an -onomy is the body of knowledge, and rules surrounding a subject of study. Once again coming to us from the ancient Greeks, it is derived from nomos, meaning law.

The most commonly confused pair of these words is probably astrology and astronomy, and they perfectly serve to explain the differences in the two suffixes. Astronomy is a field of science concerned with the physical universe. Astrology is the study of how the planets in the night sky affect our lives. While they were once considered similar, astrology was dismissed as a serious field of scientific study about 400 years ago. However, it remains a popular pastime and hobby for many. So, astronomy has genuine known rules and facts, and astrology is just a field of interest and study, with no actual scientific basis.

Some other -onomies include:

• Taxonomy – The grouping and classification of organisms
• Economy – The system and management of finances
• Gastronomy – The art or science of fine eating
• Agronomy – The science of soil management and crop production
• Isonomy – The equality of citizens under the law

And one very odd -onomy:

• Aeronomy – The study of the gasses in the upper atmosphere

Do you know of any other examples?