[ on-tol-uh-jee ]
/ ɒnˈtɒl ə dʒi /


the branch of metaphysics that studies the nature of existence or being as such.
(loosely) metaphysics.

Nearby words

  1. ontogeny,
  2. ontological,
  3. ontological argument,
  4. ontologism,
  5. ontologize,
  6. onuf's nucleus,
  7. onus,
  8. onus probandi,
  9. onward,
  10. onwards

Origin of ontology

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

Related formson·to·log·i·cal [on-tl-oj-i-kuh l] /ˌɒn tlˈɒdʒ ɪ kəl/, on·to·log·ic, on·tol·o·gis·tic [on-tol-uh-jis-tik] /ɒnˌtɒl əˈdʒɪs tɪk/, adjectiveon·tol·o·gist, noun

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ontology

British Dictionary definitions for ontology


/ (ɒnˈtɒlədʒɪ) /


philosophy the branch of metaphysics that deals with the nature of being
logic the set of entities presupposed by a theory
Derived Formsontological, adjectiveontologically, adverb

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

Word Origin and History for ontology



"metaphysical science or study of being," 1660s (Gideon Harvey), from Modern Latin ontologia (c.1600), from onto- + -logy.

Online Etymology Dictionary, © 2010 Douglas Harper