May ontology be defined exhaustedly and unambiguously by its language?
(1) Yes, it may if its language is defined in turn as the zero-level language. (2) The fundamental features of ontology according to the philosophical meaning of ‘ontology’ can be deduced from the formal properties of ‘zero-level language’. (3) A few interesting new corollaries are implied by the formal and axiomatic postulating ontology as the zero-level language.

“Formal ontology” is introduced first to programing languages in different ways. The most relevant one as to philosophy is as a generalization of “nth-order logic” and “nth-level language” for n=0. Then, the “zero-level language” would be a theoretical reflection on the naïve attitude to the world, after which the “things and words” coincide by themselves. That approach corresponds directly to the philosophical phenomenology of Husserl or fundamental ontology of Heidegger. Ontology as the 0-level language may be researched as a formal ontology.