The best replacement for ontology is epistemology.

The best alternatives to ontology are rated as following:
★★★★★  epistemology
★★★★★  taxonomy
★★★★  metaphysics
★★  deontology
★★  existentialism
★  thesaurus
★  phenomenology
★  teleology
★  cosmology
★  general metaphysics
  controlled vocabulary
  ontogeny
  vocabulary
  ontic
  semantic network
  data model

Your alternative for ontology is not listed? Suggest!
Speaking about ontology, one probably shouldn't forget about protege.

Other search terms related to ontology and their ratings are:
★★★★★ protege
★★★ ethics
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