Ontology is the study of being. It focuses on the nature of reality.


Samuel Johnson’s 1755 Dictionary did not include ontology.[2]

Webster’s 1828 Dictionary defined ontology as:[3]
“That part of the science of metaphysics which investigates and explains the nature and essence of all beings, their qualities and attributes.”

Merriam-Webster’s online dictionary defined ontology as:[4]
1 – “a branch of metaphysics concerned with the nature and relations of being”
2 – “a particular theory about the nature of being or the kinds of things that have existence”

Dictionary.com defined ontology as:[5]
1 – “the branch of metaphysics that studies the nature of existence or being as such.”
2 – “(loosely) metaphysics.”

Lexico.com defined ontology as:[6]
1 – “[mass noun] The branch of metaphysics dealing with the nature of being.”
2 – “A set of concepts and categories in a subject area or domain that shows their properties and the relations between them.”

Charles Roe (2012) defined ontology as:[1]
“the study or theory of being or that which is.”


Early C17th: The earliest known use of the word ontology in written form was created. It was based on Latin ontologia.[1]

1660s: “”the metaphysical science or study of being and the essence of things,” 1660s (Gideon Harvey), from Modern Latin ontologia (c. 1600); see onto- + -logy.”[7]

1663: “in the meaning defined at sense 1”, “New Latin ontologia, from ont- + -logia -logy”[4]

1715-25: “From the New Latin word ontologia … See onto-, -logy”[5]

Early C18th: “from modern Latin ontologia, from Greek ōn, ont- ‘being’ + -logy.”[6]


c.500 BCE: Parmenides wrote his works that are now considered the earliest works which discuss “the ontological categorization of existence”.[1]

C17th-C18th CE: According to the Etymologies section above, it was sometime during these two centuries that the word ontology was coined.



[1] – Roe, Charles. “A Short History of Ontology: It’s not just a Matter of Philosophy Anymore” (7 June 2012). https://www.dataversity.net/a-short-history-of-ontology-its-not-just-a-matter-of-philosophy-anymore/#. Accessed 16 Jan. 2021.

[2] – “A Dictionary of the English Language”, A Digital Edition of the 1755 Classic by Samuel Johnson. https://johnsonsdictionaryonline.com/search-johnsons-dictionary/?SearchValue=ontology. Accessed 16 Jan. 2021.

[3] – Webster’s 1828 Dictionary. http://webstersdictionary1828.com/Dictionary/ontology. Accessed 16 Jan. 2021.

[4] – “Ontology.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ontology. Accessed 16 Jan. 2021.

[5] – Dictionary.com. https://www.dictionary.com/browse/ontology?s=t. Accessed 16 Jan. 2021.

[6] – Lexico.com. https://www.lexico.com/definition/ontology. Accessed 16 Jan. 2021.

[7] – Online Etymology Dictionary. https://www.etymonline.com/word/ontology. Accessed 16 Jan 2021.

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2 Comments on “Ontology

  1. I reviewed the references paraphrased under the History heading on 1/25/2021 at 11:30 am, and found what appear to be errors or obscurity in the first two points paraphrasing the historical background given in Charles Roe’s article 1. You write “Pythagoras is commonly hailed as the inventor of the word ontology.” However, Roe is referring to the world “philosophy” as being coined by Pythagoras, not “ontology.” It is also unclear to me what you mean by “Pythagoras was Ionian and so technically he invented the term from which ontology is fundamentally translated.” That is, I don’t see how the second clause follows from the first, as you imply it does. Aside from a possible non-sequitur, I also don’t understand what you are deriving in your statement from Roe, besides P.’s Ionian origin, which doesn’t itself seem to need support from this data science article. 2. Roe writes that Parmenides is given credit for being the FIRST to discuss ontological categories, but you omit the “first” distinction (although this seems to be a style choice, with “first” being implied by context and dating).

    Liked by 1 person

    • Thank you for pointing that out. I’ve edited the article to make it more accurate. Also thank you for emailing me. For some reason the bot put your comment in the spam folder. I’m going to see what I can do about fixing that. I made a note of the issue on the Start Here page


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