# ontology

> English word · Noun · IPA /ɒnˈtɒləd͡ʒi/ · frequency rank #31,275

## Definitions
1. The branch of metaphysics that addresses the nature or essential characteristics of being and of things that exist; the study of being qua being.
2. In a subject view, or a world view, the set of conceptual or material things or classes of things that are recognised as existing, or are assumed to exist in context, and their interrelations; in a body of theory, the ontology comprises the domain of discourse, the things that are defined as existing, together with whatever emerges from their mutual implications.
3. The theory of a particular philosopher or school of thought concerning the fundamental types of entity in the universe.
4. A logical system involving theory of classes, developed by Stanislaw Lesniewski (1886-1939).
5. A structure of concepts or entities within a domain, organized by relationships; a system model.

## Etymology
Learned borrowing from New Latin ontologia (1606, Ogdoas Scholastica, by Jacob Lorhard (Lorhardus)), from Ancient Greek ὤν, ὄντος (ṓn, óntos, “being”), present participle of εἰμί (eimí, “being, existing, essence”) + λόγος (lógos, “account”). By surface analysis, onto- + -logy.
First known English use 1663: Archelogia philosophica nova; or, New principles of Philosophy. Containing Philosophy in general, Metaphysicks or Ontology, Dynamilogy or a Discourse of Power, Religio Philosophi or Natural Theology, Physicks or Natural philosophy, by Gideon Harvey (1636–1702), London, Thomson, 1663.
Popularized as a philosophical term by German philosopher Christian Wolff (1679–1754).

## Easily confused with
- **oncology** (https://plainspell.com/en/vs/oncology-vs-ontology)

## Common misspellings (12)
`notology`, `onntology`, `onotlogy`, `ontloogy`, `ontolgoy`, `ontollogy`, `ontologgy`, `ontologyy`, `ontoloyg`, `ontoolgy`, `onttology`, `otnology`

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/ontology