I've been going around saying that Kant invented the term ontology because, you know, they say so. Wikipedia now says
While the etymology is Greek, the oldest extant record of the word itself is the Latin form ontologia, which appeared in 1606, in the work Ogdoas Scholastica by Jacob Lorhard (Lorhardus) and in 1613 in the Lexicon philosophicum by Rudolf Göckel (Goclenius).
The first occurrence in English of "ontology" as recorded by the OED (Oxford English Dictionary, second edition, 1989) appears in Bailey’s dictionary of 1721, which defines ontology as ‘an Account of being in the Abstract’ - though, of course, such an entry indicates the term was already in use at the time. It is likely the word was first used in its Latin form by philosophers based on the Latin roots, which themselves are based on the Greek. The current on-line edition of the OED (Draft Revision September 2008) gives as first occurrence in English a work by Gideon Harvey (1636/7-1702): 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 - London, Thomson, 1663.