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Synonyms

ontology

American  
[on-tol-uh-jee] / ɒnˈtɒl ə dʒi /

noun

  1. the branch of metaphysics that studies the nature of existence or being as such.

  2. (loosely) metaphysics.


ontology British  
/ ɒnˈtɒlədʒɪ /

noun

  1. philosophy the branch of metaphysics that deals with the nature of being

  2. logic the set of entities presupposed by a theory

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of ontology

From the New Latin word ontologia, dating back to 1715–25. See onto-, -logy

Explanation

If you are interested in metaphysics and the meaning of existence (and want to impress your friends), ontology may be a good field of study for you. Ontology comes from two Greek words: on, which means "being," and logia, which means "study." So ontology is the study of being alive and existing. Heady stuff, but something we all ponder at one point or another. When you see the word ontology, think of Hamlet agonizing over "To be, or not to be" or Descartes stating "I think, therefore I am."

Keep Reading on Vocabulary.com

Vocabulary lists containing ontology

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

At the heart of all these disputes is a question of ontology, the branch of metaphysics concerned with the nature of reality.

From The Wall Street Journal Jul. 24, 2026

Analysts and Palantir refer to the ontology as an organization’s “digital twin,” where data is mapped onto real-world objects.

From Barron's Mar. 20, 2026

The deeper risk is that we may be optimizing the wrong thing by improving algorithms while leaving the underlying computational ontology unchanged.

From Science Daily Dec. 24, 2025

Many Nigerians believe in the supernatural, and this often stems from the animistic ontology that undergirds self and being in many Nigerian communities.

From New York Times Feb. 7, 2024

These were the great, complex questions of ontology that tormented him.

From "Catch-22" by Joseph Heller

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