Alright, if you got that conclusion from existence of dictionaries, what do you get from this fact:

Wittgenstein, who's considered one of most brilliant philosophers of XX century, in _Philosophical Investigations_ (widely regarded as the most important book of 20th-century philosophy) does not provide definitions, but instead goes through a series of examples, remarks, etc. In preface he notes that this structure is deliberate and he could not write it differently. The topic of the book includes philosophy of language ("the concepts of meaning, of understanding, of a proposition, of logic, the foundations of mathematics, states of consciousness,...").

His earlier book _Tractatus Logico-Philosophicus_ was very definition-heavy. And, obviously, Wittgenstein was well aware of things like dictionaries, and, well, all philosophical works up to that point. He's not the guy who's just slacking.

Another thing to note is that attempts to build AI using definitions of words failed, and not for a lack of trying. (E.g. Cyc project is running since 1980s: https://en.wikipedia.org/wiki/Cyc). OTOH LLMs which derive word meaning from usage rather than definition seems to work quite well.